高考数学（理）二轮专题突破演练（浙江专版）第3部分 专题1 第2讲“2道”拉分题专练卷1 Word版含解析.doc

“2道”拉分题专练卷(一)1已知函数f(x)ln xax2(2a)x.(1)讨论f(x)的单调性；(2)设a>0，证明：当0<x<时，f>f；(3)若函数yf(x)的图像与x轴交于A，B两点，线段AB中点的横坐标为x0，证明：f(x0)<0.解：(1)f(x)的定义域为(0，)，f(x)2ax(2a).若a0，则f(x)>0，所以f(x)在(0，)上单调递增；若a>0，则由f(x)0得x，且当x时，f(x)>0；当x>时，f(x)<0，所以f(x)在上单调递增，在上单调递减(2)证明：设函数g(x)ff，则g(x)ln(1ax)ln(1ax)2ax，g(x)2a.当0<x<时，g(x)>0，而g(0)0，所以g(x)>0，故当0<x<时，f>f.(3)证明：由(1)可得，当a0时，函数yf(x)的图像与x轴至多有一个交点，故a>0，从而f(x)的最大值为f，且f>0.不妨设A(x1,0)，B(x2,0)，0<x1<x2，则0<x1<<x2.由(2)得f f>f(x1)0.从而x2>x1，于是x0>.由(1)知，f(x0)<0.2在平面直角坐标系中，已知焦距为4的椭圆C：1(a>b>0)的左、右顶点分别为A、B，右焦点为F，过F作垂直于x轴的直线与椭圆相交于R、S两点，若线段RS的长为.(1)求椭圆C的方程；(2)设Q(9，m)是直线x9上的点，直线QA、QB与椭圆C分别交于点M、N，求证：直线MN必过x轴上的一定点，并求出此定点的坐标解：(1)依题意，椭圆过点，故解得所以椭圆C的方程为1.(2)由题意知，直线QA的方程为y(x3)，代入椭圆方程，得(80m2)x26m2x9m27200，设M(x1，y1)，则3x1x1，所以y1(x13)，故点M的坐标为.待添加的隐藏文字内容2同理，直线QB的方程为y(x3)，代入椭圆方程，得(20m2)x26m2x9m21800，设N(x2，y2)，则3x2x2，所以y2(x23)，故点N的坐标为.若m240，直线MN的方程为x1，与x轴交于点(1,0)；若m240，直线MN的方程为y，令y0，解得x1.综上所述，直线MN必过x轴上的定点(1,0)高考资源网版权所有！投稿可联系QQ：108459180129C91AFE4CED1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFEDD1B6C87D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF95AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9D1B6C8795AD9C91AFE4CED1B6C8795A1AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFC91FE4CED1D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6CD1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF8795AD9C91FE4CED1D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C87D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF5D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFAD9C91FE4CED1B6C8795AD29C91AFB6C8795AD29C91AFB6C8795AD29C91AFD1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFFE4CED1B6C8795AD29C91AFC8795AD9C91FE4CED1B6C8795AD29C91AFD1B6C8795AD9C91AFED1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8D1B6C8795AD9C91AFE4CED1D91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFC91FE4CED1D1B6C871AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFC91FE4CED1D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6CD1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF8795AD9C91FE4CED1D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C87D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF5D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFAD9C91FE4CED1B6C8795AD29C91AFB6C8795AD29C91AFB6C8795AD29C91AFD1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8791AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFC91FE4CED1D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6CD1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF8795AD9C91FE4CED1D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C87D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF5D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFAD9C91FE4CED1B6C8795AD29C91AFB6C8795AD29C91AFB6C8795AD29C91AFD1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFFE4CED1B6C8795AD29C91AFC8795AD9C91FE4CED1B6C8795AD29C91AFD1B6C8795AD9C91AFED1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8D1B6C8795AD9C91AFE4CED15AD9C91D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFFE4CED1B6C8795AD29C91AFC8795AD9C91FE4CED1B6C8795AD29C91AFD1B6C8795AD9C91AFED1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8D1B6C8795AD9C91AFE4CED195AD9C91AFE4CED1B6C8795AD91AFE4CED1B6CD1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF8795AD9C91FE4CED1D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C87D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF5D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFAD9C91FE4CED1B6C8795AD29C91AFB6C8795AD29C91AFB6C8795AD29C91AFD1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFFE4CED1B6C8795AD29C91AFC8795AD9C91FE4CED1B6C8795AD29C91AFD1B6C8795AD9C91AFED1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF795AD9C91FE4CED1B6C8795ADD1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF29C91AF4CED1B6C8795AD1B6C8795AD9C91AFE4CED1B6C8795AD91AFD1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFD1B6C8795AD29C91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C9D1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF1AFD1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AFD1BD1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF1B6C8795AD9C91AFE4CED1B6C8795AD91AFE4CED1B6C8795AD9C91FE4CED1B6C8795AD29C91AF4CED1B6C8795AD29C91AFE4CED1B6C8795ADC6F554C62