| | |
| | | <template> |
| | | <div class="chapter" num="2"> |
| | | <div class="chapter" num="3"> |
| | | <!-- 第二单元首页 --> |
| | | <div class="page-box" page="38"> |
| | | <div v-if="showPageList.indexOf(38) > -1"> |
| | |
| | | <p> |
| | | <span class="zt-ls"><b>例1</b></span> 已知<i>a</i>><i>b</i>>0. |
| | | </p> |
| | | <p>(1) 比较2<i>a</i>与2<i>b</i>的大小;</p> |
| | | <p>(2) 比较-2<i>a</i>与-2<i>b</i>的大小;</p> |
| | | <p>(3) 比较<i>ac</i>与<i>bc</i>的大小.</p> |
| | | <p> |
| | | <p class="p-btn"> |
| | | (1) 比较2a与2b的大小; |
| | | <span class="btn-box" @click="isShowAnswer0 = !isShowAnswer0"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p v-if="isShowAnswer0"> |
| | | <span class="zt-ls"><b>解</b></span>(1) 因为<i>a</i>><i>b</i>,2>0,根据性质2,有2<i>a</i>>2<i>b</i>. |
| | | </p> |
| | | <p> |
| | | <p class="p-btn"> |
| | | (2) 比较-2a与-2b的大小; |
| | | <span class="btn-box" @click="isShowAnswer1 = !isShowAnswer1"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p v-if="isShowAnswer1"> |
| | | <span class="zt-ls"><b>解</b></span> |
| | | (2) |
| | | 因为<i>a</i>><i>b</i>,-2<0,根据性质3,有-2<i>a</i><-2<i>b</i>. |
| | | </p> |
| | | <p>(3) 若<i>c</i>>0,根据性质2,有<i>ac</i>><i>bc</i>.</p> |
| | | <p class="p-btn"> |
| | | (3) 比较ac与bc的大小. |
| | | <span class="btn-box" @click="isShowAnswer2 = !isShowAnswer2"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer2"> |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> |
| | | (3) 若<i>c</i>>0,根据性质2,有<i>ac</i>><i>bc</i>. |
| | | </p> |
| | | <p>若<i>c</i><0,根据性质3,有<i>ac</i><<i>bc</i>.</p> |
| | | <p>若<i>c</i>=0,则有<i>ac</i>=<i>bc</i>=0,所以<i>ac</i>=<i>bc</i>.</p> |
| | | <p> |
| | | <span class="zt-ls"><b>例2</b></span> 已知<i>a</i>><i>b</i>,比较<i>a</i>-1与<i>b</i>-2的大小. |
| | | </div> |
| | | <p class="p-btn"> |
| | | <span class="zt-ls"><b>例2</b></span> |
| | | <span class="t1">已知a>b,比较a-1与b-2的大小.</span> |
| | | <span class="btn-box" @click="isShowAnswer3 = !isShowAnswer3"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer3"> |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> 因为<i>a</i>><i>b</i>,-1>-2, |
| | | </p> |
| | | <p>根据推论1,有<i>a</i>+(-1)><i>b</i>+(-2),</p> |
| | | <p>即<i>a</i>-1><i>b</i>-2.</p> |
| | | </div> |
| | | </div> |
| | | </div> |
| | | </div> |
| | |
| | | <p> |
| | | 因为(<i>a</i><sup>2</sup>+1)-2<i>a</i>=<i>a</i><sup>2</sup>-2<i>a</i>+1=(<i>a</i>-1)<sup>2</sup>,且当<i>a</i>≠1时,(<i>a</i>-1)<sup>2</sup>>0,所以<i>a</i><sup>2</sup>+1>2<i>a</i>. |
| | | </p> |
| | | <p> |
| | | <span class="zt-ls"><b>例1</b></span> 分析本节“问题提出”中的问题. |
| | | <p class="p-btn"> |
| | | <span class="zt-ls"><b>例1</b></span> |
| | | <span class="t1">分析本节“问题提出”中的问题.</span> |
| | | <span class="btn-box" @click="isShowAnswer4 = !isShowAnswer4"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer4"> |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> 作差可得<math display="0"> |
| | | <mfrac> |
| | |
| | | <mn>2</mn> |
| | | </math>,所以立起脚尖后,该芭蕾舞演员的下半身长与全身长的比值更接近0.618. |
| | | </p> |
| | | </div> |
| | | <div class="bk"> |
| | | <div class="bj1"> |
| | | <p class="left"> |
| | |
| | | </math>. |
| | | </p> |
| | | </div> |
| | | |
| | | <p> |
| | | <span class="zt-ls"><b>例2</b></span> 已知<i>b</i>><i>a</i>>0,<i>c</i>>0,比较<math display="0"> |
| | | <p class="p-btn"> |
| | | <span class="zt-ls"><b>例2</b></span> |
| | | <span calss="t1">已知b>a>0,c>0,比较</span> |
| | | <math display="0"> |
| | | <mfrac> |
| | | <mrow> |
| | | <mi>a</mi> |
| | |
| | | <mi>b</mi> |
| | | </mfrac> |
| | | </math>的大小. |
| | | <span class="btn-box" @click="isShowAnswer5 = !isShowAnswer5"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer5"> |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> 作差可得<math display="0"> |
| | | <mfrac> |
| | |
| | | </mfrac> |
| | | </math>. |
| | | </p> |
| | | </div> |
| | | <div class="bk-hzjl"> |
| | | <div class="bj1-hzjl"> |
| | | <p class="left"> |
| | |
| | | 区间也是一个集合,它是实数集的一个子集.但并非所有的数集都能用区间表示.例如,集合{1,3,4,5,7,8,11,12}、自然数集<b>N</b>、整数集<b>Z</b>就不能用区间表示. |
| | | </p> |
| | | </div> |
| | | <p> |
| | | <span class="zt-ls"><b>例1</b></span> 把下列集合用区间表示出来,并指出区间的类型. |
| | | <p class="p-btn"> |
| | | <span class="zt-ls"><b>例1</b></span> |
| | | <span class="t1">把下列集合用区间表示出来,并指出区间的类型.</span> |
| | | <span class="btn-box" @click="isShowAnswer6 = !isShowAnswer6"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p>(1) {<i>x</i>|-3≤<i>x</i>≤1};(2) {<i>x</i>|-1<<i>x</i><2};</p> |
| | | <p> |
| | |
| | | </math>; |
| | | </p> |
| | | <p>(5) {<i>x</i>|<i>x</i>≥2};(6) {<i>x</i>|<i>x</i><1}.</p> |
| | | <div v-if="isShowAnswer6"> |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span>(1) [-3,1],是闭区间; |
| | | </p> |
| | |
| | | </p> |
| | | <p>(5) [2,+∞),是左闭右开区间;</p> |
| | | <p>(6)(-∞,1),是开区间.</p> |
| | | <p> |
| | | <span class="zt-ls"><b>例2</b></span> 用区间表示不等式3<i>x</i><9<i>x</i>+4的解集,并在数轴上表示出来. |
| | | </div> |
| | | <p class="p-btn"> |
| | | <span class="zt-ls"><b>例2</b></span> |
| | | <span class="t1">用区间表示不等式3<i>x</i><9<i>x</i>+4的解集,并在数轴上表示出来.</span> |
| | | <span class="btn-box" @click="isShowAnswer7 = !isShowAnswer7"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer7"> |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> 解不等式3<i>x</i><9<i>x</i>+4,得 |
| | | </p> |
| | |
| | | </p> |
| | | <p class="center"><img class="img-f" alt="" src="../../assets/images/0050-7.jpg" /></p> |
| | | <p class="img">图2-1</p> |
| | | <p> |
| | | <span |
| | | class="zt-ls"><b>例3</b></span> 设<b>R</b>为全集,集合<i>A</i>={<i>x</i>|-5<<i>x</i><6},<i>B</i>={<i>x</i>|<i>x</i>≥3或<i>x</i>≤-3},用区间表示<i>A</i>∩<i>B</i>. |
| | | </div> |
| | | <p class="p-btn"> |
| | | <span class="zt-ls"><b>例3</b></span> |
| | | <span class="t1">设<b>R</b>为全集,集合A={x|-5<x<6},B={x|x≥3或x≤-3},用区间表示A∩B.</span> |
| | | <span class="btn-box" @click="isShowAnswer8 = !isShowAnswer8"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer8"> |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> |
| | | 在数轴上将集合<i>A</i>,<i>B</i>表示出来,如图2-2所示. |
| | |
| | | </p> |
| | | <p>={<i>x</i>|-5<<i>x</i>≤-3}∪{<i>x</i>|3≤<i>x</i><6}</p> |
| | | <p>=(-5,-3]∪[3,6).</p> |
| | | </div> |
| | | </div> |
| | | </div> |
| | | </div> |
| | |
| | | </div> |
| | | <h3 id="c015">习题2.2<span class="fontsz2">>>></span></h3> |
| | | <div class="bj"> |
| | | <examinations :cardList="questionData[47] ? questionData[47][2] : []" :hideCollect="true" sourceType="json" inputBc="#d3edfa" |
| | | v-if="questionData"></examinations> |
| | | <examinations :cardList="questionData[47] ? questionData[47][2] : []" :hideCollect="true" sourceType="json" |
| | | inputBc="#d3edfa" v-if="questionData"></examinations> |
| | | </div> |
| | | <h2 id="b009"> |
| | | 2.3 一元二次不等式<span class="fontsz1">>>>>>>>></span> |
| | |
| | | </math>,与<i>y</i>轴的交点坐标为(0,<i>c</i>). |
| | | </p> |
| | | </div> |
| | | <p><b>例</b> 已知二次函数<i>y</i>=<i>x</i><sup>2</sup>-2<i>x</i>-3,</p> |
| | | <p>(1) 画出该函数图像;</p> |
| | | <p> |
| | | <p class="p-btn"> |
| | | <b>例</b> |
| | | <span>已知二次函数<i>y</i>=<i>x</i><sup>2</sup>-2<i>x</i>-3,</span> |
| | | <span class="btn-box" @click="openDialog(thinkOne)"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.545" height="18.112" viewBox="0 0 20.545 22.112"> |
| | | <path class="a" |
| | | d="M3771.2-14311.889a2.356,2.356,0,0,1-1.727-.626c-.027-.054-.053-.1-.079-.148l0-.007c-.123-.224-.2-.371-.076-.629a.869.869,0,0,1,.784-.471.205.205,0,0,1,.158.079.205.205,0,0,0,.158.079.187.187,0,0,0,.038.1.143.143,0,0,0,.117.05h.158a.573.573,0,0,0,.471.158,2.2,2.2,0,0,0,.916-.3l.023-.011a.572.572,0,0,1,.471-.158.575.575,0,0,1,.626.626.526.526,0,0,1,.036.409.664.664,0,0,1-.349.375A3.582,3.582,0,0,1,3771.2-14311.889Zm-1.885-1.723h-.155a.718.718,0,0,1-.784-.63.38.38,0,0,1-.021-.3.976.976,0,0,1,.492-.485l4.86-1.252a1.047,1.047,0,0,1,.784.626c.151.3-.128.61-.471.784l-4.705,1.256Zm-.155-1.885H3769a.716.716,0,0,1-.784-.626c-.149-.3.129-.611.471-.784l4.234-1.1v-.158l-.021.007a7.808,7.808,0,0,1-1.861.31,5.3,5.3,0,0,1-3.137-.942,5.789,5.789,0,0,1-2.666-4.076,6.421,6.421,0,0,1,1.256-5.018,7.038,7.038,0,0,1,2.194-1.568,7.848,7.848,0,0,1,2.666-.472,6.43,6.43,0,0,1,2.979.784,4.958,4.958,0,0,1,2.2,2.194,5.522,5.522,0,0,1,.313,5.177,13.113,13.113,0,0,1-1.256,1.882l-.313.313a2.156,2.156,0,0,0-.78,1.244l0,.012a1.731,1.731,0,0,1-1.727,1.723l-.313.158-3.292.939Zm1.256-6.271v1.256h1.41v-1.256Zm.784-4.234c.718,0,1.1.271,1.1.784a.925.925,0,0,1-.316.783l-.468.156a2.235,2.235,0,0,0-.63.471l-.012.024a2.2,2.2,0,0,0-.3.918v.155h1.1v-.155a1.2,1.2,0,0,1,.313-.629.543.543,0,0,0,.315-.153c.007,0,.315,0,.315-.16a1.226,1.226,0,0,0,.626-.626,2.277,2.277,0,0,0,.313-1.1,1.409,1.409,0,0,0-.626-1.252,2.337,2.337,0,0,0-1.569-.471,2.258,2.258,0,0,0-2.507,2.353l1.252.154A1.121,1.121,0,0,1,3771.2-14326Zm-6.51,9.645a.769.769,0,0,1-.549-.237.772.772,0,0,1-.235-.549.772.772,0,0,1,.235-.548l.939-.939a.781.781,0,0,1,.55-.234.772.772,0,0,1,.547.234.772.772,0,0,1,.238.549.772.772,0,0,1-.238.549l-.939.938A.769.769,0,0,1,3764.686-14316.356Zm13.174-.157a.774.774,0,0,1-.549-.234l-.943-.942a.678.678,0,0,1-.233-.47.678.678,0,0,1,.233-.47.774.774,0,0,1,.549-.234.774.774,0,0,1,.549.234l.942.939a.427.427,0,0,1,.228.324.74.74,0,0,1-.228.618A.774.774,0,0,1,3777.859-14316.514Zm2.9-6.351h-1.414c-.469-.158-.784-.474-.784-.784a.743.743,0,0,1,.784-.784h1.414a.743.743,0,0,1,.784.784A.743.743,0,0,1,3780.761-14322.864Zm-17.566-.158h-1.41c-.469-.157-.784-.473-.784-.784a.743.743,0,0,1,.784-.784h1.41a.743.743,0,0,1,.784.784A.743.743,0,0,1,3763.195-14323.022Zm13.861-5.723a.759.759,0,0,1-.529-.237.776.776,0,0,1-.235-.549.772.772,0,0,1,.235-.549l.939-.938a.44.44,0,0,1,.413-.238.759.759,0,0,1,.529.238.772.772,0,0,1,.235.549.772.772,0,0,1-.235.548l-.942.939A.435.435,0,0,1,3777.055-14328.745Zm-11.429,0a.776.776,0,0,1-.55-.237l-.939-1.1a.678.678,0,0,1-.235-.469.678.678,0,0,1,.235-.47.772.772,0,0,1,.549-.238.772.772,0,0,1,.549.238l.939,1.1a.675.675,0,0,1,.238.47.675.675,0,0,1-.238.47A.767.767,0,0,1,3765.626-14328.745Zm5.724-2.273a.743.743,0,0,1-.784-.785v-1.413c.157-.469.473-.784.784-.784a.743.743,0,0,1,.784.784v1.413A.743.743,0,0,1,3771.35-14331.019Z" |
| | | transform="translate(-3761 14334.001)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p class="p-btn"> |
| | | (1) 画出该函数图像; |
| | | <span class="btn-box" @click="isShowAnswer9 = !isShowAnswer9"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p class="p-btn"> |
| | | (2) |
| | | 指出该函数图像上纵坐标分别为<i>y</i>=0,<i>y</i>>0,<i>y</i><0的所有点; |
| | | 指出该函数图像上纵坐标分别为y=0,y>0,y<0的所有点; |
| | | <span class="btn-box" @click="isShowAnswer10 = !isShowAnswer10"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p> |
| | | <p class="p-btn"> |
| | | (3) |
| | | 根据函数图像写出<i>y</i>=0,<i>y</i>>0,<i>y</i><0时所对应的<i>x</i>的值或取值范围. |
| | | 根据函数图像写出y=0,y>0,y<0时所对应的x的值或取值范围. |
| | | <span class="btn-box" @click="isShowAnswer11 = !isShowAnswer11"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p class="block"> |
| | | <span |
| | | class="zt-ls2"><b>分析</b></span> ①根据<i>x</i><sup>2</sup>的系数判断函数图像(抛物线)的开口方向;②用判别式判定出一元二次方程<i>x</i><sup>2</sup>-2<i>x</i>-3=0的解的情况,从而确定二次函数<i>y</i>=<i>x</i><sup>2</sup>-2<i>x</i>-3的图像与<i>x</i>轴的交点个数和交点坐标;③计算二次函数图像的顶点坐标、与<i>y</i>轴的交点坐标;④求出二次函数图像的对称轴方程,并利用函数图像的对称性再找出一些点;⑤最后根据上述信息画出函数图像. |
| | | </p> |
| | | <p class="block"> |
| | | 画出图像后,<i>y</i>=0,<i>y</i>>0,<i>y</i><0分别对应函数图像与<i>x</i>轴相交、函数图像在<i>x</i>轴上方、函数图像在<i>x</i>轴下方三种情形,根据图像完成(2)(3) |
| | | 两个问题. |
| | | </p> |
| | | <iframe src="https://www.geogebra.org/calculator" frameborder="0" class="iframe-box"></iframe> |
| | | </div> |
| | | </div> |
| | | </div> |
| | |
| | | <li>上册</li> |
| | | </ul> |
| | | <div class="padding-116"> |
| | | <div v-if="isShowAnswer9"> |
| | | <p class="center"><img class="img-c" alt="" src="../../assets/images/0055-1.jpg" /></p> |
| | | <p class="img">图2-3</p> |
| | | <p> |
| | |
| | | <p> |
| | | 根据以上信息,就可以画出函数<i>y</i>=<i>x</i><sup>2</sup>-2<i>x</i>-3的图像(如图2-3所示). |
| | | </p> |
| | | <p> |
| | | </div> |
| | | <p v-if="isShowAnswer10"> |
| | | (2) |
| | | 观察图像可知,满足<i>y</i>=0的点是抛物线与<i>x</i>轴的交点;满足<i>y</i>>0的点是抛物线在<i>x</i>轴上方的所有点;满足<i>y</i><0的点是抛物线在<i>x</i>轴下方的所有点. |
| | | </p> |
| | | <div v-if="isShowAnswer11"> |
| | | <p> |
| | | (3) |
| | | 观察图像可知,当<i>y</i>=0时,对应抛物线与<i>x</i>轴的两个交点,此时<i>x</i>有两个取值,<i>x</i><sub>1</sub>=-1,<i>x</i><sub>2</sub>=3; |
| | |
| | | <p> |
| | | 当<i>y</i><0时,对应抛物线在<i>x</i>轴下方的所有点,此时<i>x</i>的取值范围是-1<<i>x</i><3. |
| | | </p> |
| | | </div> |
| | | <div class="bk-hzjl"> |
| | | <div class="bj1-hzjl"> |
| | | <p class="left"> |
| | | <img class="img-gn2" alt="" src="../../assets/images/hzjl.jpg" /> |
| | | </p> |
| | | </div> |
| | | <examinations :cardList="questionData[51] ? questionData[51][1] : []" :hideCollect="true" sourceType="json" inputBc="#d3edfa" |
| | | v-if="questionData"></examinations> |
| | | <examinations :cardList="questionData[51] ? questionData[51][1] : []" :hideCollect="true" sourceType="json" |
| | | inputBc="#d3edfa" v-if="questionData"></examinations> |
| | | </div> |
| | | <p class="left"><img class="img-gn" alt="" src="../../assets/images/stlx.jpg" /></p> |
| | | <div class="bj"> |
| | | <p>已知下列二次函数:</p> |
| | | <p>①<i>y</i>=<i>x</i><sup>2</sup>-3<i>x</i>-4, ②<i>y</i>=<i>x</i><sup>2</sup>+<i>x</i>+2, ③<i>y</i>=<i>x</i><sup>2</sup>-6<i>x</i>+9.</p> |
| | | <p>①<i>y</i>=<i>x</i><sup>2</sup>-3<i>x</i>-4, ②<i>y</i>=<i>x</i><sup>2</sup>+<i>x</i>+2, |
| | | ③<i>y</i>=<i>x</i><sup>2</sup>-6<i>x</i>+9.</p> |
| | | <p>(1) 分别画出它们的函数图像;</p> |
| | | <paint |
| | | :page="51" |
| | | :imgUrl="this.config.activeBook.resourceUrl + '/images/a6fe3d63.png'" |
| | | /> |
| | | <paint :page="51" :imgUrl="this.config.activeBook.resourceUrl + '/images/a6fe3d63.png'" /> |
| | | <p> |
| | | (2) 根据函数图像写出<i>y</i>=0,<i>y</i>>0,<i>y</i><0时所对应的<i>x</i>的值或取值范围. |
| | | <span class="btn-box" @click="isShowAnswer = !isShowAnswer"> |
| | |
| | | <ul class="table-answer-box" v-if="isShowAnswer"> |
| | | <li>答案:</li> |
| | | <li> |
| | | <math display="block"> <mrow> <mo>①</mo> </mrow> <mi>y</mi> <mo>=</mo> <msup> <mi>x</mi> <mrow> <mn>2</mn> </mrow> </msup> <mo>−</mo> <mn>3</mn> <mi>x</mi> <mo>−</mo> <mn>4</mn> <mo>=</mo> <mo stretchy="false">(</mo> <mi>x</mi> <mo>+</mo> <mn>1</mn> <mo stretchy="false">)</mo> <mo stretchy="false">(</mo> <mi>x</mi> <mo>−</mo> <mn>4</mn> <mo stretchy="false">)</mo></math> |
| | | <math display="block"> <mo>当</mo> <mi>y</mi> <mo>=</mo> <mn>0</mn> <mo>时,</mo> <msub> <mi>x</mi> <mrow> <mn>1</mn> </mrow> </msub> <mo>=</mo> <mo>−</mo> <mn>1</mn> <mo>或</mo> <msub> <mi>x</mi> <mrow> <mn>2</mn> </mrow> </msub> <mo>=</mo> <mn>4</mn> <mo>,</mo></math> |
| | | <math display="block"> <mo>当</mo> <mi>y</mi> <mo>></mo> <mn>0</mn> <mo>时,</mo> <mi>x</mi> <mo><</mo> <mo>−</mo> <mn>1</mn> <mo>或</mo> <mi>x</mi> <mo>></mo> <mn>4</mn> <mo>,</mo></math> |
| | | <math display="block"> <mo>当</mo> <mi>y</mi> <mo><</mo> <mn>0</mn> <mo>时,</mo> <mo>−</mo> <mn>1</mn> <mo><</mo> <mi>x</mi> <mo><</mo> <mn>4</mn> <mo>;</mo></math> |
| | | <math display="block"> <mo>因此当</mo> <mi>y</mi> <mo>=</mo> <mn>0</mn> <mo>时,所对应的点为</mo> <mo stretchy="false">(</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> <mo>,</mo> <mo stretchy="false">(</mo> <mn>4</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> <mo>;</mo> <mo>当</mo> <mi>y</mi> <mo>></mo> <mn>0</mn> <mo>时,所对应的点为</mo> </math> |
| | | <math display="block"> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mrow> <mn>0</mn> </mrow> </msub> <mo>,</mo> <mi>y</mi> <mo stretchy="false">)</mo> <mo>,其中,</mo> <msub> <mi>x</mi> <mrow> <mn>0</mn> </mrow> </msub> <mo><</mo> <mo>−</mo> <mn>1</mn> <mo>或</mo> <msub> <mi>x</mi> <mrow> <mn>0</mn> </mrow> </msub> <mo>></mo> <mn>4</mn> <mo>;</mo> </math> |
| | | <math display="block"> <mo>当</mo> <mi>y</mi> <mo><</mo> <mn>0</mn> <mo>时,所对应的点为</mo> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mrow> <mn>0</mn> </mrow> </msub> <mo>,</mo> <mi>y</mi> <mo stretchy="false">)</mo> <mo>,其中</mo> <mo>−</mo> <mn>1</mn> <mo><</mo> <msub> <mi>x</mi> <mrow> <mn>0</mn> </mrow> </msub> <mo><</mo> <mn>4</mn> <mo>;</mo></math> |
| | | <math display="block"> <mrow> <mo>②</mo> </mrow> <mi>y</mi> <mo>=</mo> <msup> <mi>x</mi> <mrow> <mn>2</mn> </mrow> </msup> <mo>+</mo> <mi>x</mi> <mo>+</mo> <mn>2</mn> <mo>=</mo> <mo stretchy="false">(</mo> <mi>x</mi> <mo>+</mo> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <msup> <mo stretchy="false">)</mo> <mrow> <mn>2</mn> </mrow> </msup> <mo>+</mo> <mfrac> <mn>7</mn> <mn>4</mn> </mfrac> <mo>></mo> <mn>0</mn> <mo>;</mo></math> |
| | | <math display="block"> <mo>当</mo> <mi>y</mi> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mi>y</mi> <mo><</mo> <mn>0</mn> <mo>时,没有对应的点;当</mo> <mi>y</mi> <mo>></mo> <mn>0</mn> <mo>时,所对应的点为</mo> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mrow> <mn>0</mn> </mrow> </msub> <mo>,</mo> <mi>y</mi> <mo stretchy="false">)</mo> </math> |
| | | <math> <mo>,其中</mo> <msub> <mi>x</mi> <mrow> <mn>0</mn> </mrow> </msub> <mo>∈</mo> <mi>R</mi> <mo>.</mo></math> |
| | | <math display="block"> <mrow> <mo>③</mo> </mrow> <mi>y</mi> <mo>=</mo> <msup> <mi>x</mi> <mrow> <mn>2</mn> </mrow> </msup> <mo>−</mo> <mn>6</mn> <mi>x</mi> <mo>+</mo> <mn>9</mn> <mo>=</mo> <mo stretchy="false">(</mo> <mi>x</mi> <mo>−</mo> <mn>3</mn> <msup> <mo stretchy="false">)</mo> <mrow> <mn>2</mn> </mrow> </msup> <mo>.</mo></math> |
| | | <math display="block"> <mo>当</mo> <mi>y</mi> <mo>=</mo> <mn>0</mn> <mo>时</mo> <mo>,</mo> <mo>所对应的点为</mo> <mo stretchy="false">(</mo> <mn>3</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> <mo>;当</mo> <mi>y</mi> <mo>></mo> <mn>0</mn> <mo>时,所对应的点为</mo> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mrow> <mn>0</mn> </mrow> </msub> <mo>,</mo> <mi>y</mi> <mo stretchy="false">)</mo> </math> |
| | | <math display="block"> <mo>,其中</mo> <msub> <mi>x</mi> <mrow> <mn>0</mn> </mrow> </msub> <mo>≠</mo> <mn>3</mn> <mo>;当</mo> <mi>y</mi> <mo><</mo> <mn>0</mn> <mo>时,没有对应的点</mo> <mo>.</mo></math> |
| | | <math display="block"> |
| | | <mrow> |
| | | <mo>①</mo> |
| | | </mrow> |
| | | <mi>y</mi> |
| | | <mo>=</mo> |
| | | <msup> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>2</mn> |
| | | </mrow> |
| | | </msup> |
| | | <mo>−</mo> |
| | | <mn>3</mn> |
| | | <mi>x</mi> |
| | | <mo>−</mo> |
| | | <mn>4</mn> |
| | | <mo>=</mo> |
| | | <mo stretchy="false">(</mo> |
| | | <mi>x</mi> |
| | | <mo>+</mo> |
| | | <mn>1</mn> |
| | | <mo stretchy="false">)</mo> |
| | | <mo stretchy="false">(</mo> |
| | | <mi>x</mi> |
| | | <mo>−</mo> |
| | | <mn>4</mn> |
| | | <mo stretchy="false">)</mo> |
| | | </math> |
| | | <math display="block"> |
| | | <mo>当</mo> |
| | | <mi>y</mi> |
| | | <mo>=</mo> |
| | | <mn>0</mn> |
| | | <mo>时,</mo> |
| | | <msub> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>1</mn> |
| | | </mrow> |
| | | </msub> |
| | | <mo>=</mo> |
| | | <mo>−</mo> |
| | | <mn>1</mn> |
| | | <mo>或</mo> |
| | | <msub> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>2</mn> |
| | | </mrow> |
| | | </msub> |
| | | <mo>=</mo> |
| | | <mn>4</mn> |
| | | <mo>,</mo> |
| | | </math> |
| | | <math display="block"> |
| | | <mo>当</mo> |
| | | <mi>y</mi> |
| | | <mo>></mo> |
| | | <mn>0</mn> |
| | | <mo>时,</mo> |
| | | <mi>x</mi> |
| | | <mo><</mo> |
| | | <mo>−</mo> |
| | | <mn>1</mn> |
| | | <mo>或</mo> |
| | | <mi>x</mi> |
| | | <mo>></mo> |
| | | <mn>4</mn> |
| | | <mo>,</mo> |
| | | </math> |
| | | <math display="block"> |
| | | <mo>当</mo> |
| | | <mi>y</mi> |
| | | <mo><</mo> |
| | | <mn>0</mn> |
| | | <mo>时,</mo> |
| | | <mo>−</mo> |
| | | <mn>1</mn> |
| | | <mo><</mo> |
| | | <mi>x</mi> |
| | | <mo><</mo> |
| | | <mn>4</mn> |
| | | <mo>;</mo> |
| | | </math> |
| | | <math display="block"> |
| | | <mo>因此当</mo> |
| | | <mi>y</mi> |
| | | <mo>=</mo> |
| | | <mn>0</mn> |
| | | <mo>时,所对应的点为</mo> |
| | | <mo stretchy="false">(</mo> |
| | | <mo>−</mo> |
| | | <mn>1</mn> |
| | | <mo>,</mo> |
| | | <mn>0</mn> |
| | | <mo stretchy="false">)</mo> |
| | | <mo>,</mo> |
| | | <mo stretchy="false">(</mo> |
| | | <mn>4</mn> |
| | | <mo>,</mo> |
| | | <mn>0</mn> |
| | | <mo stretchy="false">)</mo> |
| | | <mo>;</mo> |
| | | <mo>当</mo> |
| | | <mi>y</mi> |
| | | <mo>></mo> |
| | | <mn>0</mn> |
| | | <mo>时,所对应的点为</mo> |
| | | </math> |
| | | <math display="block"> |
| | | <mo stretchy="false">(</mo> |
| | | <msub> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>0</mn> |
| | | </mrow> |
| | | </msub> |
| | | <mo>,</mo> |
| | | <mi>y</mi> |
| | | <mo stretchy="false">)</mo> |
| | | <mo>,其中,</mo> |
| | | <msub> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>0</mn> |
| | | </mrow> |
| | | </msub> |
| | | <mo><</mo> |
| | | <mo>−</mo> |
| | | <mn>1</mn> |
| | | <mo>或</mo> |
| | | <msub> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>0</mn> |
| | | </mrow> |
| | | </msub> |
| | | <mo>></mo> |
| | | <mn>4</mn> |
| | | <mo>;</mo> |
| | | </math> |
| | | <math display="block"> |
| | | <mo>当</mo> |
| | | <mi>y</mi> |
| | | <mo><</mo> |
| | | <mn>0</mn> |
| | | <mo>时,所对应的点为</mo> |
| | | <mo stretchy="false">(</mo> |
| | | <msub> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>0</mn> |
| | | </mrow> |
| | | </msub> |
| | | <mo>,</mo> |
| | | <mi>y</mi> |
| | | <mo stretchy="false">)</mo> |
| | | <mo>,其中</mo> |
| | | <mo>−</mo> |
| | | <mn>1</mn> |
| | | <mo><</mo> |
| | | <msub> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>0</mn> |
| | | </mrow> |
| | | </msub> |
| | | <mo><</mo> |
| | | <mn>4</mn> |
| | | <mo>;</mo> |
| | | </math> |
| | | <math display="block"> |
| | | <mrow> |
| | | <mo>②</mo> |
| | | </mrow> |
| | | <mi>y</mi> |
| | | <mo>=</mo> |
| | | <msup> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>2</mn> |
| | | </mrow> |
| | | </msup> |
| | | <mo>+</mo> |
| | | <mi>x</mi> |
| | | <mo>+</mo> |
| | | <mn>2</mn> |
| | | <mo>=</mo> |
| | | <mo stretchy="false">(</mo> |
| | | <mi>x</mi> |
| | | <mo>+</mo> |
| | | <mfrac> |
| | | <mn>1</mn> |
| | | <mn>2</mn> |
| | | </mfrac> |
| | | <msup> |
| | | <mo stretchy="false">)</mo> |
| | | <mrow> |
| | | <mn>2</mn> |
| | | </mrow> |
| | | </msup> |
| | | <mo>+</mo> |
| | | <mfrac> |
| | | <mn>7</mn> |
| | | <mn>4</mn> |
| | | </mfrac> |
| | | <mo>></mo> |
| | | <mn>0</mn> |
| | | <mo>;</mo> |
| | | </math> |
| | | <math display="block"> |
| | | <mo>当</mo> |
| | | <mi>y</mi> |
| | | <mo>=</mo> |
| | | <mn>0</mn> |
| | | <mo>,</mo> |
| | | <mi>y</mi> |
| | | <mo><</mo> |
| | | <mn>0</mn> |
| | | <mo>时,没有对应的点;当</mo> |
| | | <mi>y</mi> |
| | | <mo>></mo> |
| | | <mn>0</mn> |
| | | <mo>时,所对应的点为</mo> |
| | | <mo stretchy="false">(</mo> |
| | | <msub> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>0</mn> |
| | | </mrow> |
| | | </msub> |
| | | <mo>,</mo> |
| | | <mi>y</mi> |
| | | <mo stretchy="false">)</mo> |
| | | </math> |
| | | <math> |
| | | <mo>,其中</mo> |
| | | <msub> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>0</mn> |
| | | </mrow> |
| | | </msub> |
| | | <mo>∈</mo> |
| | | <mi>R</mi> |
| | | <mo>.</mo> |
| | | </math> |
| | | <math display="block"> |
| | | <mrow> |
| | | <mo>③</mo> |
| | | </mrow> |
| | | <mi>y</mi> |
| | | <mo>=</mo> |
| | | <msup> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>2</mn> |
| | | </mrow> |
| | | </msup> |
| | | <mo>−</mo> |
| | | <mn>6</mn> |
| | | <mi>x</mi> |
| | | <mo>+</mo> |
| | | <mn>9</mn> |
| | | <mo>=</mo> |
| | | <mo stretchy="false">(</mo> |
| | | <mi>x</mi> |
| | | <mo>−</mo> |
| | | <mn>3</mn> |
| | | <msup> |
| | | <mo stretchy="false">)</mo> |
| | | <mrow> |
| | | <mn>2</mn> |
| | | </mrow> |
| | | </msup> |
| | | <mo>.</mo> |
| | | </math> |
| | | <math display="block"> |
| | | <mo>当</mo> |
| | | <mi>y</mi> |
| | | <mo>=</mo> |
| | | <mn>0</mn> |
| | | <mo>时</mo> |
| | | <mo>,</mo> |
| | | <mo>所对应的点为</mo> |
| | | <mo stretchy="false">(</mo> |
| | | <mn>3</mn> |
| | | <mo>,</mo> |
| | | <mn>0</mn> |
| | | <mo stretchy="false">)</mo> |
| | | <mo>;当</mo> |
| | | <mi>y</mi> |
| | | <mo>></mo> |
| | | <mn>0</mn> |
| | | <mo>时,所对应的点为</mo> |
| | | <mo stretchy="false">(</mo> |
| | | <msub> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>0</mn> |
| | | </mrow> |
| | | </msub> |
| | | <mo>,</mo> |
| | | <mi>y</mi> |
| | | <mo stretchy="false">)</mo> |
| | | </math> |
| | | <math display="block"> |
| | | <mo>,其中</mo> |
| | | <msub> |
| | | <mi>x</mi> |
| | | <mrow> |
| | | <mn>0</mn> |
| | | </mrow> |
| | | </msub> |
| | | <mo>≠</mo> |
| | | <mn>3</mn> |
| | | <mo>;当</mo> |
| | | <mi>y</mi> |
| | | <mo><</mo> |
| | | <mn>0</mn> |
| | | <mo>时,没有对应的点</mo> |
| | | <mo>.</mo> |
| | | </math> |
| | | </li> |
| | | </ul> |
| | | </div> |
| | |
| | | 上面的情形表明,二次函数图像的开口方向及其与<i>x</i>轴的交点坐标,可以确定其对应的一元二次不等式的解集. |
| | | </p> |
| | | <p><b>例</b> 利用二次函数的图像解下列一元二次不等式.</p> |
| | | <p> |
| | | (1) -<i>x</i><sup>2</sup>+3<i>x</i>+4<0;(2) <i>x</i><sup>2</sup>-2<i>x</i>+3>0. |
| | | <p class="p-btn" > |
| | | <span>(1) -<i>x</i><sup>2</sup>+3<i>x</i>+4<0;</span> |
| | | <span class="btn-box" @click="isShowAnswer12 = !isShowAnswer12"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p class="p-btn" > |
| | | <span>(2) <i>x</i><sup>2</sup>-2<i>x</i>+3>0.</span> |
| | | <span class="btn-box" @click="isShowAnswer13 = !isShowAnswer13"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <iframe src="https://www.geogebra.org/calculator" frameborder="0" class="iframe-box"></iframe> |
| | | <div v-if="isShowAnswer12" > |
| | | <p class="center"><img class="img-c" alt="" src="../../assets/images/0057-1.jpg" /></p> |
| | | <p class="img">图2-5</p> |
| | | <p> |
| | |
| | | <p> |
| | | 函数<i>y</i>=-<i>x</i><sup>2</sup>+3<i>x</i>+4的图像是开口向下的抛物线,与<i>x</i>轴的交点坐标是(-1,0),(4,0),函数<i>y</i>=-<i>x</i><sup>2</sup>+3<i>x</i>+4的图像如图2-5所示. |
| | | </p> |
| | | </div> |
| | | <div v-if="isShowAnswer13" > |
| | | <p class="center"><img class="img-c" alt="" src="../../assets/images/0057-2.jpg" /></p> |
| | | <p class="img">图2-6</p> |
| | | <p> |
| | |
| | | <p> |
| | | 观察图像可得,不等式<i>x</i><sup>2</sup>-2<i>x</i>+3>0的解集为<b>R</b>. |
| | | </p> |
| | | </div> |
| | | <div class="bk"> |
| | | <div class="bj1"> |
| | | <p class="left"> |
| | |
| | | <img class="img-gn2" alt="" src="../../assets/images/hzjl.jpg" /> |
| | | </p> |
| | | </div> |
| | | <examinations :cardList="questionData[54] ? questionData[54][1] : []" :hideCollect="true" sourceType="json" v-if="questionData"> |
| | | <examinations :cardList="questionData[54] ? questionData[54][1] : []" :hideCollect="true" sourceType="json" |
| | | v-if="questionData"> |
| | | </examinations> |
| | | </div> |
| | | <p class="left"><img class="img-gn" alt="" src="../../assets/images/cxgk.jpg" /></p> |
| | |
| | | </p> |
| | | <p>第三步:观察简图,写出不等式的解集.</p> |
| | | <div class="bj"> |
| | | <examinations :cardList="questionData[54] ? questionData[54][2] : []" :hideCollect="true" sourceType="json" inputBc="#d3edfa" |
| | | v-if="questionData"></examinations> |
| | | <examinations :cardList="questionData[54] ? questionData[54][2] : []" :hideCollect="true" sourceType="json" |
| | | inputBc="#d3edfa" v-if="questionData"></examinations> |
| | | </div> |
| | | </div> |
| | | </div> |
| | |
| | | <p> |
| | | <span class="zt-ls"><b>例1</b></span> 解下列不等式. |
| | | </p> |
| | | <p> |
| | | (1)(<i>x</i>+3)(<i>x</i>+1)<0;(2)(6-<i>x</i>)(<i>x</i>+4)≤0. |
| | | <p class="p-btn" > |
| | | <span>(1)(<i>x</i>+3)(<i>x</i>+1)<0;</span> |
| | | <span class="btn-box" @click="isShowAnswer14 = !isShowAnswer14"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p class="p-btn" > |
| | | <span>(2)(6-<i>x</i>)(<i>x</i>+4)≤0.</span> |
| | | <span class="btn-box" @click="isShowAnswer15 = !isShowAnswer15"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer14" > |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span>(1)(<i>x</i>+3)(<i>x</i>+1)<0,即[<i>x</i>-(-3)][<i>x</i>-(-1)]<0. |
| | | </p> |
| | | <p>所以不等式的解集为(-3,-1).</p> |
| | | </div> |
| | | <div v-if="isShowAnswer15" > |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> |
| | | (2) |
| | | 由(6-<i>x</i>)(<i>x</i>+4)≤0得(<i>x</i>-6)(<i>x</i>+4)≥0,即 |
| | | </p> |
| | | <p class="center">(<i>x</i>-6)[<i>x</i>-(-4)]≥0.</p> |
| | | <p>所以不等式的解集为(-∞,-4]∪[6,+∞).</p> |
| | | <p> |
| | | </div> |
| | | <p class="p-btn" > |
| | | <span> |
| | | <span class="zt-ls"><b>例2</b></span> 解下列不等式. |
| | | </span> |
| | | <span class="btn-box" @click="openDialog(thinkTwo)"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.545" height="18.112" viewBox="0 0 20.545 22.112"> |
| | | <path class="a" |
| | | d="M3771.2-14311.889a2.356,2.356,0,0,1-1.727-.626c-.027-.054-.053-.1-.079-.148l0-.007c-.123-.224-.2-.371-.076-.629a.869.869,0,0,1,.784-.471.205.205,0,0,1,.158.079.205.205,0,0,0,.158.079.187.187,0,0,0,.038.1.143.143,0,0,0,.117.05h.158a.573.573,0,0,0,.471.158,2.2,2.2,0,0,0,.916-.3l.023-.011a.572.572,0,0,1,.471-.158.575.575,0,0,1,.626.626.526.526,0,0,1,.036.409.664.664,0,0,1-.349.375A3.582,3.582,0,0,1,3771.2-14311.889Zm-1.885-1.723h-.155a.718.718,0,0,1-.784-.63.38.38,0,0,1-.021-.3.976.976,0,0,1,.492-.485l4.86-1.252a1.047,1.047,0,0,1,.784.626c.151.3-.128.61-.471.784l-4.705,1.256Zm-.155-1.885H3769a.716.716,0,0,1-.784-.626c-.149-.3.129-.611.471-.784l4.234-1.1v-.158l-.021.007a7.808,7.808,0,0,1-1.861.31,5.3,5.3,0,0,1-3.137-.942,5.789,5.789,0,0,1-2.666-4.076,6.421,6.421,0,0,1,1.256-5.018,7.038,7.038,0,0,1,2.194-1.568,7.848,7.848,0,0,1,2.666-.472,6.43,6.43,0,0,1,2.979.784,4.958,4.958,0,0,1,2.2,2.194,5.522,5.522,0,0,1,.313,5.177,13.113,13.113,0,0,1-1.256,1.882l-.313.313a2.156,2.156,0,0,0-.78,1.244l0,.012a1.731,1.731,0,0,1-1.727,1.723l-.313.158-3.292.939Zm1.256-6.271v1.256h1.41v-1.256Zm.784-4.234c.718,0,1.1.271,1.1.784a.925.925,0,0,1-.316.783l-.468.156a2.235,2.235,0,0,0-.63.471l-.012.024a2.2,2.2,0,0,0-.3.918v.155h1.1v-.155a1.2,1.2,0,0,1,.313-.629.543.543,0,0,0,.315-.153c.007,0,.315,0,.315-.16a1.226,1.226,0,0,0,.626-.626,2.277,2.277,0,0,0,.313-1.1,1.409,1.409,0,0,0-.626-1.252,2.337,2.337,0,0,0-1.569-.471,2.258,2.258,0,0,0-2.507,2.353l1.252.154A1.121,1.121,0,0,1,3771.2-14326Zm-6.51,9.645a.769.769,0,0,1-.549-.237.772.772,0,0,1-.235-.549.772.772,0,0,1,.235-.548l.939-.939a.781.781,0,0,1,.55-.234.772.772,0,0,1,.547.234.772.772,0,0,1,.238.549.772.772,0,0,1-.238.549l-.939.938A.769.769,0,0,1,3764.686-14316.356Zm13.174-.157a.774.774,0,0,1-.549-.234l-.943-.942a.678.678,0,0,1-.233-.47.678.678,0,0,1,.233-.47.774.774,0,0,1,.549-.234.774.774,0,0,1,.549.234l.942.939a.427.427,0,0,1,.228.324.74.74,0,0,1-.228.618A.774.774,0,0,1,3777.859-14316.514Zm2.9-6.351h-1.414c-.469-.158-.784-.474-.784-.784a.743.743,0,0,1,.784-.784h1.414a.743.743,0,0,1,.784.784A.743.743,0,0,1,3780.761-14322.864Zm-17.566-.158h-1.41c-.469-.157-.784-.473-.784-.784a.743.743,0,0,1,.784-.784h1.41a.743.743,0,0,1,.784.784A.743.743,0,0,1,3763.195-14323.022Zm13.861-5.723a.759.759,0,0,1-.529-.237.776.776,0,0,1-.235-.549.772.772,0,0,1,.235-.549l.939-.938a.44.44,0,0,1,.413-.238.759.759,0,0,1,.529.238.772.772,0,0,1,.235.549.772.772,0,0,1-.235.548l-.942.939A.435.435,0,0,1,3777.055-14328.745Zm-11.429,0a.776.776,0,0,1-.55-.237l-.939-1.1a.678.678,0,0,1-.235-.469.678.678,0,0,1,.235-.47.772.772,0,0,1,.549-.238.772.772,0,0,1,.549.238l.939,1.1a.675.675,0,0,1,.238.47.675.675,0,0,1-.238.47A.767.767,0,0,1,3765.626-14328.745Zm5.724-2.273a.743.743,0,0,1-.784-.785v-1.413c.157-.469.473-.784.784-.784a.743.743,0,0,1,.784.784v1.413A.743.743,0,0,1,3771.35-14331.019Z" |
| | | transform="translate(-3761 14334.001)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p> |
| | | (1)(<i>x</i>+1)<sup>2</sup>≥4;(2)(2<i>x</i>-3)<sup>2</sup><9. |
| | | <p class="p-btn" > |
| | | <span>(1)(<i>x</i>+1)<sup>2</sup>≥4;</span> |
| | | <span class="btn-box" @click="isShowAnswer16 = !isShowAnswer16"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p class="block"> |
| | | <span |
| | | class="zt-ls2"><b>分析</b></span> 由(<i>x</i>+1)<sup>2</sup>≥4得<i>x</i><sup>2</sup>+2<i>x</i>+1≥4,即<i>x</i><sup>2</sup>+2<i>x</i>-3≥0,从而可以利用二次函数<i>y</i>=<i>x</i><sup>2</sup>+2<i>x</i>-3的图像进行求解;注意到4=2<sup>2</sup>,也可以考虑将(<i>x</i>+1)<sup>2</sup>≥4整理为(<i>x</i>+1)<sup>2</sup>-4≥0,并使用平方差公式,即(<i>x</i>+1)<sup>2</sup>-2<sup>2</sup>≥0,得到(<i>x</i>+3)(<i>x</i>-1)≥0,此时可以借助上面的结论直接求解.下面我们将使用后一种方法进行求解. |
| | | <p class="p-btn" > |
| | | <span>(2)(2<i>x</i>-3)<sup>2</sup><9.</span> |
| | | <span class="btn-box" @click="isShowAnswer17 = !isShowAnswer17"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer16" > |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span>(1) |
| | | 由(<i>x</i>+1)<sup>2</sup>≥4得(<i>x</i>+1)<sup>2</sup>-2<sup>2</sup>≥0, |
| | |
| | | <p>化简得(<i>x</i>+3)(<i>x</i>-1)≥0,</p> |
| | | <p>即 [<i>x</i>-(-3)](<i>x</i>-1)≥0,</p> |
| | | <p>所以不等式的解集为(-∞,-3]∪[1,+∞).</p> |
| | | </div> |
| | | <div v-if="isShowAnswer17" > |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> |
| | | (2) |
| | | 由(2<i>x</i>-3)<sup>2</sup><9得(2<i>x</i>-3)<sup>2</sup>-3<sup>2</sup><0, |
| | | </p> |
| | |
| | | <p>即 <i>x</i>(<i>x</i>-3)<0,</p> |
| | | <p>即(<i>x</i>-0)(<i>x</i>-3)<0,</p> |
| | | <p>所以不等式的解集为(0,3).</p> |
| | | </div> |
| | | <p class="left"><img class="img-gn" alt="" src="../../assets/images/stlx.jpg" /></p> |
| | | <div class="bj"> |
| | | <p>解下列一元二次不等式.</p> |
| | |
| | | </li> |
| | | </ul> |
| | | <div class="padding-116"> |
| | | <p><b>例</b> 解不等式|2<i>x</i>|<5.</p> |
| | | <p class="p-btn" > |
| | | <span> |
| | | <b>例</b> 解不等式|2<i>x</i>|<5. |
| | | </span> |
| | | <span class="btn-box" @click="isShowAnswer18 = !isShowAnswer18"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer18" > |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> |
| | | 由|2<i>x</i>|<5得-5<2<i>x</i><5, |
| | |
| | | </mrow> |
| | | </math>. |
| | | </p> |
| | | </div> |
| | | <div class="bk-hzjl"> |
| | | <div class="bj1-hzjl"> |
| | | <p class="left"> |
| | | <img class="img-gn2" alt="" src="../../assets/images/hzjl.jpg" /> |
| | | </p> |
| | | </div> |
| | | <examinations :cardList="questionData[60] ? questionData[60][1] : []" :hideCollect="true" sourceType="json" inputBc="#d3edfa" |
| | | v-if="questionData"></examinations> |
| | | <examinations :cardList="questionData[60] ? questionData[60][1] : []" :hideCollect="true" sourceType="json" |
| | | inputBc="#d3edfa" v-if="questionData"></examinations> |
| | | </div> |
| | | <p class="left"> |
| | | <img class="img-gn" alt="" src="../../assets/images/stlx.jpg" /> |
| | | </p> |
| | | <div class="bj"> |
| | | <examinations :cardList="questionData[60] ? questionData[60][2] : []" :hideCollect="true" sourceType="json" inputBc="#d3edfa" |
| | | v-if="questionData"></examinations> |
| | | <examinations :cardList="questionData[60] ? questionData[60][2] : []" :hideCollect="true" sourceType="json" |
| | | inputBc="#d3edfa" v-if="questionData"></examinations> |
| | | </div> |
| | | <h3 id="c021"> |
| | | 2.4.2 |
| | |
| | | <p> |
| | | 求解此类不等式时,可以将<i>ax</i>+<i>b</i>看作一个整体,再利用含绝对值不等式的基本解法,去掉绝对值,然后进行求解. |
| | | </p> |
| | | <p> |
| | | <p class="p-btn" > |
| | | <span> |
| | | <span class="zt-ls"><b>例1</b></span> 解不等式|2<i>x</i>-1|<5. |
| | | </span> |
| | | <span class="btn-box" @click="isShowAnswer19 = !isShowAnswer19"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer19" > |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> |
| | | 由|2<i>x</i>-1|<5得-5<2<i>x</i>-1<5, |
| | |
| | | <p>即 -4<2<i>x</i><6,</p> |
| | | <p> -2<<i>x</i><3.</p> |
| | | <p>所以不等式的解集是(-2,3).</p> |
| | | <p> |
| | | </div> |
| | | <p class="p-btn" > |
| | | <span> |
| | | <span class="zt-ls"><b>例2</b></span> 解不等式|1-2<i>x</i>|<3. |
| | | </span> |
| | | <span class="btn-box" @click="isShowAnswer20 = !isShowAnswer20"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer20" > |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> 因为|1-2<i>x</i>|=|2<i>x</i>-1|, |
| | | </p> |
| | | <p>所以由|1-2<i>x</i>|<3得|2<i>x</i>-1|<3.</p> |
| | | <p>由|2<i>x</i>-1|<3得-3<2<i>x</i>-1<3,</p> |
| | | <p>即 -2<2<i>x</i><4,</p> |
| | | <p> -1<<i>x</i><2.</p> |
| | | <p>所以不等式的解集是(-1,2).</p> |
| | | </div> |
| | | </div> |
| | | </div> |
| | | </div> |
| | |
| | | <li>上册</li> |
| | | </ul> |
| | | <div class="padding-116"> |
| | | <p>由|2<i>x</i>-1|<3得-3<2<i>x</i>-1<3,</p> |
| | | <p>即 -2<2<i>x</i><4,</p> |
| | | <p> -1<<i>x</i><2.</p> |
| | | <p>所以不等式的解集是(-1,2).</p> |
| | | <p> |
| | | <p class="p-btn" > |
| | | <span> |
| | | <span class="zt-ls"><b>例3</b></span> 解不等式|<i>x</i>+3|≥2. |
| | | </span> |
| | | <span class="btn-box" @click="isShowAnswer21 = !isShowAnswer21"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer21" > |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> |
| | | 由|<i>x</i>+3|≥2得<i>x</i>+3≤-2或<i>x</i>+3≥2, |
| | |
| | | 时,李先生按照产权登记面积结算房款;如果产权登记面积小于97 |
| | | m<sup>2</sup>或大于103 m<sup>2</sup>时,李先生有权退房. |
| | | </p> |
| | | <p> |
| | | </div> |
| | | <p class="p-btn" > |
| | | <span> |
| | | <span class="zt-ls"><b>例4</b></span> 解不等式|3<i>x</i>-(<i>x</i>-2)|≤2. |
| | | </span> |
| | | <span class="btn-box" @click="isShowAnswer22 = !isShowAnswer22"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer22"> |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> |
| | | 由|3<i>x</i>-(<i>x</i>-2)|≤2得|3<i>x</i>-<i>x</i>+2|≤2, |
| | |
| | | <p> -4≤2<i>x</i>≤0,</p> |
| | | <p> -2≤<i>x</i>≤0.</p> |
| | | <p>所以不等式的解集是[-2,0].</p> |
| | | </div> |
| | | <p class="left"><img class="img-gn" alt="" src="../../assets/images/stlx.jpg" /></p> |
| | | <div class="bj"> |
| | | <examinations :cardList="questionData[61]" :hideCollect="true" sourceType="json" inputBc="#d3edfa" |
| | |
| | | </h3> |
| | | <p class="center"><img class="img-c" alt="" src="../../assets/images/0066-11.jpg" /></p> |
| | | <p class="img">图2-12</p> |
| | | <p> |
| | | <p class="p-btn" > |
| | | <span> |
| | | <span class="zt-ls"><b>例1</b></span> 用篱笆在墙边围一块矩形小花坛,其中一边靠墙(如图2-12所示),篱笆总长为8m.若小花坛的面积不小于6 |
| | | m<sup>2</sup>,则小花坛垂直于墙的一边的长度范围是多少? |
| | | </span> |
| | | <span class="btn-box" @click="isShowAnswer23 = !isShowAnswer23"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p> |
| | | <p v-if="isShowAnswer23" > |
| | | <span class="zt-ls"><b>解</b></span> |
| | | 设小花坛垂直于墙的一边的长度为<i>x</i>(m),则与墙平行的一边的长度为(8-2<i>x</i>)m.考虑到实际情况,有<i>x</i>>0,并且8-2<i>x</i>>0,所以<i>x</i>满足0<<i>x</i><4. |
| | | </p> |
| | |
| | | <li>上册</li> |
| | | </ul> |
| | | <div class="padding-116"> |
| | | <div v-if="isShowAnswer23"> |
| | | <p>设小花坛的面积为<i>S</i>(m<sup>2</sup>),则</p> |
| | | <p class="center"><i>S</i>=<i>x</i>(8-2<i>x</i>),</p> |
| | | <p class="center"><img class="img-c" alt="" src="../../assets/images/0067-1.jpg" /></p> |
| | |
| | | {<i>x</i>|0<<i>x</i><4}∩{<i>x</i>|1≤<i>x</i>≤3}={<i>x</i>|1≤<i>x</i>≤3}. |
| | | </p> |
| | | <p>所以小花坛垂直于墙的一边的长度在1m至3m之间(含1m和3m).</p> |
| | | <p> |
| | | </div> |
| | | <p class="p-btn" > |
| | | <span> |
| | | <span |
| | | class="zt-ls"><b>例2</b></span> 某网店销售一种电动玩具,成本为10元/个.平时按单价20元销售,日平均销售量为100个.为进一步提升业绩,该网店决定在“双11”期间举办降价促销活动.根据以往的统计,如果该电动玩具的单价每降低0.5元,日平均销售量就会大约增加10个.为了使促销活动期间日平均利润不低于平时,应如何确定降价的范围? |
| | | </span> |
| | | <span class="btn-box" @click="isShowAnswer24 = !isShowAnswer24"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
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| | | transform="translate(-3761 14334.001)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p class="block"> |
| | | <span |
| | | class="zt-ls2"><b>分析</b></span> 利润=(销售单价-成本单价)×销售量.降价过程中,单价降低能够使销售量变大,但也使销售单价与成本单价的差减小,所以降价的范围应保证利润不低于促销前. |
| | | </p> |
| | | <div class="bk"> |
| | | <div class="bk mt-60" > |
| | | <div class="bj1"> |
| | | <p class="left"> |
| | | <img class="img-gn1" alt="" src="../../assets/images/tbts.jpg" /> |
| | |
| | | 由例1和例2可知,在解决与一元二次不等式有关的实际问题时,不仅要解一元二次不等式,而且要考虑实际背景对未知数的限制.在例1中,实际背景对未知数的限制是0<<i>x</i><4;在例2中,实际背景对未知数的限制是0<<i>x</i><10. |
| | | </p> |
| | | </div> |
| | | <div v-if="isShowAnswer24"> |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> |
| | | 假设降价<i>x</i>元.考虑到实际情况,价格的降幅应小于10元,即保证销售价高于成本价,所以要求<i>x</i>>0并且<i>x</i><10,即0<<i>x</i><10. |
| | |
| | | <p> |
| | | 由于0<<i>x</i><10,所以<i>x</i>的范围是{<i>x</i>|0<<i>x</i><10}∩{<i>x</i>|0≤<i>x</i>≤5},即{<i>x</i>|0<<i>x</i>≤5}.所以降价的范围应在0至5元之间(含5元,不含0元),即单价定在15元至20元之间(含15元,不含20元),便能满足要求. |
| | | </p> |
| | | </div> |
| | | <div class="bk-hzjl"> |
| | | <div class="bj1-hzjl"> |
| | | <p class="left"> |
| | |
| | | </li> |
| | | </ul> |
| | | <div class="padding-116"> |
| | | <p class="center"><img class="img-c" alt="" src="../../assets/images/0068-1.jpg" /></p> |
| | | <p class="img">第2题图</p> |
| | | <p class="left"><img class="img-gn" alt="" src="../../assets/images/stlx.jpg" /></p> |
| | | <div class="bj"> |
| | | <examinations :cardList="questionData[64]" :hideCollect="true" sourceType="json" v-if="questionData"> |
| | |
| | | <h3 id="c024"> |
| | | 2.5.2 不等式与复杂实际问题<span class="fontsz2">>>></span> |
| | | </h3> |
| | | <p> |
| | | <p class="p-btn" > |
| | | <span> |
| | | <span |
| | | class="zt-ls"><b>例1</b></span> 我国交通法规对小型汽车驾驶员的年龄限制如下:最低年龄18周岁,最高年龄70周岁.已有研究表明,小型汽车驾驶员对红绿灯变化的反应时间<i>y</i>(ms) |
| | | 与驾驶员年龄<i>x</i>(周岁) |
| | | 的关系为<i>y</i>=0.005<i>x</i><sup>2</sup>-0.2<i>x</i>+22,其中18≤<i>x</i>≤70.问:反应时间超过24.5ms的驾驶员所处的年龄范围是多少? |
| | | </span> |
| | | <span class="btn-box" @click="isShowAnswer25 = !isShowAnswer25"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <div v-if="isShowAnswer25" > |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> 由题意得,<i>y</i>=0.005<i>x</i><sup>2</sup>-0.2<i>x</i>+22>24.5,即 |
| | | </p> |
| | |
| | | <i>ms</i> |
| | | 的驾驶员所处的年龄范围在50岁至70岁之间(不包含50岁,包含70岁). |
| | | </p> |
| | | </div> |
| | | |
| | | <p> |
| | | <span class="zt-ls"><b>例2</b></span> 身体质量指数(Body Mass |
| | | Index,BMI)是衡量人体胖瘦程度的一个常用标准,计算公式为<math display="0"> |
| | |
| | | 000m跑、女生800m跑),坐位体前屈等项目的成绩总和.身体素质指标为正数说明身体素质较好.上述研究发现,身体素质指标(<i>y</i>)与BMI(<i>x</i>) |
| | | 之间的关系如表2-7所示. |
| | | </p> |
| | | <p>问:身体素质较好的男生和女生,其BMI的范围分别是多少?</p> |
| | | <p class="p-btn" > |
| | | 问:身体素质较好的男生和女生,其BMI的范围分别是多少? |
| | | <span class="btn-box" @click="isShowAnswer26 = !isShowAnswer26"> |
| | | <svg xmlns="http://www.w3.org/2000/svg" width="16.501" height="16.501" viewBox="0 0 20.501 20.501"> |
| | | <path class="a" |
| | | d="M3344.717-15308.5H3337.4a10.186,10.186,0,0,1-7.25-3,10.185,10.185,0,0,1-3-7.25A10.262,10.262,0,0,1,3337.4-15329a10.26,10.26,0,0,1,10.249,10.248,10.129,10.129,0,0,1-2.2,6.341v3.177A.734.734,0,0,1,3344.717-15308.5Zm-9.606-7.29h4.493l.527,1.419c.071.182.156.386.254.608a2.428,2.428,0,0,0,.273.512.986.986,0,0,0,.315.262.971.971,0,0,0,.454.1,1.05,1.05,0,0,0,.773-.327,1.025,1.025,0,0,0,.319-.723,3.3,3.3,0,0,0-.277-1.051l-.062-.161-2.889-7.313c-.119-.321-.228-.607-.335-.873a2.972,2.972,0,0,0-.323-.616,1.56,1.56,0,0,0-.5-.469,1.552,1.552,0,0,0-.781-.181,1.535,1.535,0,0,0-.773.181,1.475,1.475,0,0,0-.5.477,3.674,3.674,0,0,0-.362.739l-.239.627-.054.135-2.824,7.355c-.095.229-.179.46-.25.688a1.529,1.529,0,0,0-.073.477.978.978,0,0,0,.323.72,1.039,1.039,0,0,0,.746.315.838.838,0,0,0,.716-.3,4.676,4.676,0,0,0,.466-.985l.062-.165.527-1.449Zm3.747-1.5h-3.293l1.812-5.124,1.481,5.123Z" |
| | | transform="translate(-3327.144 15329)" /> |
| | | </svg> |
| | | </span> |
| | | </p> |
| | | <p class="img">表2-7</p> |
| | | <p class="center"><img class="img-a" alt="" src="../../assets/images/0069-1.jpg" /></p> |
| | | <div v-if="isShowAnswer26" > |
| | | <p> |
| | | <span class="zt-ls"><b>解</b></span> |
| | | 先考虑男生的情况.由题意得,<i>y</i>=-0.05<i>x</i><sup>2</sup>+2<i>x</i>-19.2>0,即 |
| | |
| | | 因此,身体素质较好的男生BMI 的范围是(16,24),身体素质较好的女生BMI |
| | | 的范围是(16,23). |
| | | </p> |
| | | </div> |
| | | <div class="bk-hzjl"> |
| | | <div class="bj1-hzjl"> |
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| | | <examinations :cardList="questionData[65]" :hideCollect="true" sourceType="json" |
| | | v-if="questionData" ></examinations> |
| | | <examinations :cardList="questionData[65]" :hideCollect="true" sourceType="json" v-if="questionData"> |
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| | | <examinations :cardList="questionData[66] ? questionData[66][1] : []" :hideCollect="true" sourceType="json" inputBc="#d3edfa" |
| | | v-if="questionData"></examinations> |
| | | <examinations :cardList="questionData[66] ? questionData[66][1] : []" :hideCollect="true" sourceType="json" |
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| | | <h3 id="c025">习题2.5<span class="fontsz2">>>></span></h3> |
| | | <div class="bj"> |
| | | <examinations :cardList="questionData[66] ? questionData[66][2] : []" :hideCollect="true" sourceType="json" v-if="questionData"> |
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| | | <!-- 066 --> |
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| | | <span style=""> 分析 </span> |
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| | | d="M2.257993 493.371555 415.470783 906.584344 512 1003.113561 608.529217 906.584344 1021.742007 493.371555 925.212789 396.842337 512 810.055127 98.787211 396.842337Z" |
| | | fill="#1296db" p-id="5068" /> |
| | | <path |
| | | d="M2.257993 117.980154 415.470783 531.192944 512 627.722161 608.529217 531.192944 1021.742007 117.980154 925.212789 21.450937 512 434.663727 98.787211 21.450937Z" |
| | | fill="#1296db" p-id="5069" /> |
| | | </svg> |
| | | </div> |
| | | </el-dialog> |
| | | </div> |
| | | </template> |
| | | |
| | | <script> |
| | | const handleShow = (num) => { |
| | | const obj = {} |
| | | for (let index = 0; index < num; index++) { |
| | | obj['isShowAnswer' + index] = false |
| | | } |
| | | return obj |
| | | } |
| | | const showObj = handleShow(30) |
| | | import paint from '@/components/paint/index.vue' |
| | | import examinations from '@/components/examinations/index.vue' |
| | | export default { |
| | |
| | | components: { examinations,paint }, |
| | | data() { |
| | | return { |
| | | isShowAnswer:false |
| | | collectImg: require('../../assets/images/icon/heart.png'), |
| | | collectCheck: require('../../assets/images/icon/heart-check.png'), |
| | | thinkingDialog: false, |
| | | showIndex: 0, |
| | | thinkData: [], |
| | | thinkOne: [ |
| | | '①根据<i>x</i><sup>2</sup>的系数判断函数图像(抛物线)的开口方向;', |
| | | '②用判别式判定出一元二次方程<i>x</i><sup>2</sup>-2<i>x</i>-3=0的解的情况,从而确定二次函数<i>y</i>=<i>x</i><sup>2</sup>-2<i>x</i>-3的图像与<i>x</i>轴的交点个数和交点坐标;', |
| | | '③计算二次函数图像的顶点坐标、与<i>y</i>轴的交点坐标;', |
| | | '④求出二次函数图像的对称轴方程,并利用函数图像的对称性再找出一些点;⑤最后根据上述信息画出函数图像.', |
| | | '画出图像后,<i>y</i>=0,<i>y</i>>0,<i>y</i><0分别对应函数图像与<i>x</i>轴相交、函数图像在<i>x</i>轴上方、函数图像在<i>x</i>轴下方三种情形,根据图像完成(2)(3)两个问题.' |
| | | ], |
| | | thinkTwo:[ |
| | | '由(<i>x</i>+1)<sup>2</sup>≥4得<i>x</i><sup>2</sup>+2<i>x</i>+1≥4,即<i>x</i><sup>2</sup>+2<i>x</i>-3≥0,从而可以利用二次函数<i>y</i>=<i>x</i><sup>2</sup>+2<i>x</i>-3的图像进行求解;注意到4=2<sup>2</sup>,也可以考虑将(<i>x</i>+1)<sup>2</sup>≥4整理为(<i>x</i>+1)<sup>2</sup>-4≥0,并使用平方差公式,即(<i>x</i>+1)<sup>2</sup>-2<sup>2</sup>≥0,得到(<i>x</i>+3)(<i>x</i>-1)≥0,此时可以借助上面的结论直接求解.下面我们将使用后一种方法进行求解.' |
| | | ], |
| | | thinkThree:[ |
| | | '利润=(销售单价-成本单价)×销售量.降价过程中,单价降低能够使销售量变大,但也使销售单价与成本单价的差减小,所以降价的范围应保证利润不低于促销前.' |
| | | ], |
| | | isShowAnswer: false, |
| | | isShowAnswerOne: false, |
| | | ...showObj |
| | | }; |
| | | }, |
| | | mounted() { }, |
| | | methods: {}, |
| | | mounted() { |
| | | console.log(2, this); |
| | | }, |
| | | methods: { |
| | | openDialog(queryData) { |
| | | this.thinkData = queryData |
| | | this.thinkingDialog = !this.thinkingDialog |
| | | }, |
| | | closeDialog() { |
| | | this.showIndex = 0 |
| | | }, |
| | | changeNext() { |
| | | if (this.showIndex < this.thinkData.length - 1) this.showIndex = this.showIndex + 1 |
| | | } |
| | | }, |
| | | }; |
| | | </script> |
| | | |
| | |
| | | top: 0; |
| | | width: 140px; |
| | | } |
| | | |
| | | .question-textarea { |
| | | margin-left: 20px; |
| | | width: 94%; |
| | | border-color:#DCDFE6; |
| | | } |
| | | |
| | | .table-answer-box { |
| | | math { |
| | | width: max-content; |
| | | height: 36px; |
| | | } |
| | | } |
| | | |
| | | li { |
| | | list-style: none; |
| | | } |
| | | </style> |