(完整word版)2018年高考数学专题复习突破训练(高考真题专题练)_构造函数解决高考导数问题.pdf
构造函数解决高考导数问题1.(2015课标全国理)设函数aaxxexfx)12()(,其中1a,若存在唯一的整数0 x使得0)(0 xf,则a的取值范围是()A)1,23eB)43,23eC)43,23eD)1,23e2.(2016课标全国 II 卷理)若直线 y=kx+b 是曲线 y=lnx+2 的切线,也是曲线 y=ln(x+1)的切线,则b=3.(2016 北京理)(本小题13 分)设函数 f(x)=xaxe+bx,曲线 y=f(x)在点(2,f(2)处的切线方程为y=(e1)x+4,(I)求 a,b 的值;(II)求 f(x)的单调区间4.(2017全国 III 卷文)(12 分)已知函数()f x=lnx+ax2+(2a+1)x(1)讨论()f x的单调性;(2)当 a0 时,证明3()24f xa5.(2016?四川卷文)(本小题满分14 分)设函数 f(x)=ax2alnx,g(x)=1xeex,其中 aR,e=2.718 为自然对数的底数.()讨论f(x)的单调性;()证明:当x1 时,g(x)0;()确定a 的所有可能取值,使得f(x)g(x)在区间(1,+)内恒成立.精品资料-欢迎下载-欢迎下载 名师归纳-第 1 页,共 13 页 -6.(2016?课标全国文)(本小题满分12 分)已知函数()(1)ln(1)f xxxa x.(I)当4a时,求曲线()yfx在1,(1)f处的切线方程;()若当1,x时,()0f x,求a的取值范围.7.(2017天津文)(本小题满分14 分)设,a bR,|1a.已知函数32()63(4)f xxxa axb,()e()xg xf x.()求()f x 的单调区间;()已知函数()yg x 和xye 的图像在公共点(x0,y0)处有相同的切线,(i)求证:()f x 在0 xx 处的导数等于0;(ii)若关于 x 的不等式()exg x在区间001,1xx上恒成立,求b 的取值范围.8.(2016 江苏)(本小题满分16 分)已知函数f(x)=ax+bx(a0,b0,a1,b1)(1)设 a=2,b=12求方程 f(x)=2 的根;若对于任意xR,不等式f(2x)mf(x)6 恒成立,求实数m 的最大值;(2)若 0a1,b1,函数 g(x)=f(x)2 有且只有1 个零点,求ab 的值精品资料-欢迎下载-欢迎下载 名师归纳-第 2 页,共 13 页 -文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L29.(2016 山东理)(本小题满分13 分)已知221()ln,xf xa xxaRx.(I)讨论()f x的单调性;(II)当1a时,证明3()2f xfx对于任意的1,2x成立.10.(2017江苏文)(本小题满分16 分)已知函数3210fx=xaxbx(a,bR)有极值,且导函数fx的极值点是fx的零点.(极值点是指函数取极值时对应的自变量的值)(1)求 b 关于 a 的函数关系式,并写出定义域;(2)证明:b23a;(3)若fx,fx这两个函数的所有极值之和不小于7-2,求 a 的取值范围.精品资料-欢迎下载-欢迎下载 名师归纳-第 3 页,共 13 页 -文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2构造函数解决高考导数问题答案1.(2015课标全国理)设函数aaxxexfx)12()(,其中1a,若存在唯一的整数0 x使得0)(0 xf,则a的取值范围是()A)1,23eB)43,23eC)43,23eD)1,23e【答案】D【解析】由题意,存在唯一的整数x0,使得 f(x0)0,即存在唯一的整数x0,使0 xe(2x01)a(x01)设 g(x)ex(2x1),h(x)a(x1)g(x)ex(2x1)2exex(2x1),从而当 x,12时,g(x)单调递减;当x 12,时,g(x)单调递增又 h(x)a(x1)必过点(1,0),g(0)1,当 g(0)h(0)时,a0(1)101.而 g(1)3e,当 g(1)h(1)时,a03e1(1)32e,要满足题意,则32ea1,选 D.【点评】关键点拨:把“若存在唯一的整数x0,使得 f(x0)0”转化为“若存在唯一的整数x0,使得0 xe(2x01)a(x01)”测训诊断:本题难度较难,主要考查导数知识的应用考查转化与化归思想2.(2016课标全国II 卷理)若直线y=kx+b 是曲线y=lnx+2 的切线,也是曲线y=ln(x+)的切线,则b=【答案】1ln 2【解析】设 ykxb 切 yln x2 的切点为(x1,y1),切 yln(x1)的切点为(x2,y2)由导数的几何意义和切点的特征可知kx1bln x12y1,k1x1,kx2bln(x21)y2,k1x21.由消去 x1,y1整理可得 b1ln k,由消去 x2,y2整理可得 bln kk1.联立可得1ln k ln kk1,k2,b1ln k1ln 2.【点评】关键点拨:关于函数的切线问题,我们要利用导数的几何意义,构建等量关系还需注意切点既在函数图像上,也在切线上对于切点不明确的,需要设出切点,再合理表达精品资料-欢迎下载-欢迎下载 名师归纳-第 4 页,共 13 页 -文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2求解测训诊断:(1)利用导数的几何意义求解切线问题,是高中导数知识的重要部分,应熟练掌握基本题型,在此基础上加强综合题的训练(2)本题有一定深度,难度,考查了学生的知识迁移能力和数据处理能力,争取得分3.(2016 北京理)(本题满分13 分)设函数 f(x)=xaxe+bx,曲线 y=f(x)在点(2,f(2)处的切线方程为y=(e1)x+4,(I)求 a,b 的值;(II)求 f(x)的单调区间解:(1)因为 f(x)xea-xbx,所以 f(x)(1x)ea-xb.依题设,有f(2)2e2,f (2)e1,即2ea-22b2e2,ea-2be1.解得 a2,be.(2)由(1)知 f(x)xe2-xex,由 f(x)e2-x(1xex-1)及 e2-x0 知,f(x)与 1xex-1同号令 g(x)1xex-1,则 g(x)1ex-1.令 g(x)0,得 x1.所以当 x(,1)时,g(x)0,g(x)在区间(1,)上单调递增故 g(1)1 是 g(x)在区间(,)上的最小值,从而 g(x)0,x(,)综上可知,f(x)0,x(,)故 f(x)的单调递增区间为(,)【点评】测训诊断:(1)本题难度易,主要考查导数的几何意义和函数单调区间的求解(2)本题若失分,多是对导致的概念理解不清或计算出错4.(2017全国 III 卷文)(12 分)已知函数()f x=lnx+ax2+(2a+1)x(1)讨论()f x的单调性;(2)当 a0 时,证明3()24f xa精品资料-欢迎下载-欢迎下载 名师归纳-第 5 页,共 13 页 -文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2解:(1))0()1)(12(1)12(2)(2xxxaxxxaaxxf当0a时,0)(xf,则)(xf在),0(单调递增当0a时,则)(xf在)21,0(a单调递增,在),21(a单调递减.(2)由(1)知,当0a时,max111()()ln1224f xfaaa1311()(2)ln()12422faaaa,令tty1ln(021at),令011ty,解得1ty在)1,0(单调递增,在),1(单调递减.max(1)0yyy,即)243()(maxaxf,243)(axf.5.(2016?四川卷文)(本题满分14 分)设函数 f(x)=ax2alnx,g(x)=1xeex,其中 aR,e=2.718 为自然对数的底数.()讨论f(x)的单调性;()证明:当x1 时,g(x)0;()确定a 的所有可能取值,使得f(x)g(x)在区间(1,+)内恒成立.解:(1)f(x)2ax1x2ax21x(x0)当 a0 时,f(x)0 时,由 f(x)0 得 x12a.当 x 0,12a时,f(x)0,f(x)单调递增(2)证明:令 s(x)ex-1x,则 s(x)ex-11.当 x1 时,s(x)0,所以 ex-1x,从而 g(x)1xeex0.(3)由(2)知,当 x1 时,g(x)0.当 a0,x1 时,f(x)a(x21)ln xg(x)在区间(1,)内恒成立时,必有a0.当 0a1.由(1)有 f12a0.所以此时 f(x)g(x)在区间(1,)内不恒成立当 a12时,令 h(x)f(x)g(x)(x1),则 h(x)2ax1x1x2e1-xx1x1x21xx32x1x2x22x1x20.因此,h(x)在区间(1,)内单调递增又因为 h(1)0,所以当 x1 时,h(x)f(x)g(x)0,即 f(x)g(x)恒成立综上,a12,.【点评】关键点拨:第(1)问中对a 的讨论是关键,第(3)问中恒成立求参数化归为函数求最值,最值的求解是难点测训诊断:(1)本题难度较大,主要考查分类讨论求单调区间、构造函数证明不等式、不等式恒成立求参数取值范围问题(2)考生失分主要体现两点:分类讨论不全面;在第(3)问中不等式恒成立求参数范围转化为函数求最值时,计算过程出现失误6.(2016?课标全国文)(本小题满分12 分)已知函数()(1)ln(1)f xxxa x.(I)当4a时,求曲线()yfx在1,(1)f处的切线方程;()若当1,x时,()0f x,求a的取值范围.解:(1)f(x)的定义域为(0,),当 a4 时,f(x)(x1)ln x4(x1),f(x)ln x1x3,f(1)2,f(1)0.所以曲线 yf(x)在(1,f(1)处的切线方程为2xy20.(2)当 x(1,)时,f(x)0 等价于 ln xa(x1)x10.设 g(x)ln xa(x1)x1,则 g(x)1x2a(x1)2x22(1a)x1x(x1)2,g(1)0.当 a2,x(1,)时,x22(1a)x1 x22x10,即 g(x)0,g(x)在(1,)上单调递增,因此g(x)0;当 a2 时,令 g(x)0 得 x1a1(a1)2 1,x2a1(a 1)21.由 x21 和 x1x21 得 x11,故当 x(1,x2)时,g(x)0,g(x)在(1,x2)上单调递减,精品资料-欢迎下载-欢迎下载 名师归纳-第 7 页,共 13 页 -文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2因此 g(x)0,所以 mf(x)24f(x)对于任意 xR 恒成立精品资料-欢迎下载-欢迎下载 名师归纳-第 9 页,共 13 页 -文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文档编码:CJ3I10G6Z7T3 HS8H5F1E9Q2 ZY7E4T10O9L2文