文档介绍：历年高考数学真题精选（按考点分类）
专题六 比较大小（学生版）
(2019•新课标1)已知a = log2 , b = , c = ，则( )
A. a < b < c B. a < c < b C. c）
a < b < c
b < a < c
c < b < a
c < a < b
(2017 •天津)已知奇函数f (x)在R上是增函数，g (x) = xf (x) .若a = g (-log2 ),
b = g() , c = g (3),则a , b , c 的大小关系为( )
a < b < c
c < b < a
b < a < c
b < c < a
历年高考数学真题精选(按考点分类)
专题六 比较大小(教师版)
一．选择题(共17小题)
(2019•新课标1)已知a = , b = , c = ,3，则( )
A. a < b < c B. a < c < b C. c < a < b D. b < c < a
【答案】B
【解析】a = log < log 1 = 0， b = > 2o = 1,
•.•0 < < = 1, /. c = (0,1), :.a < c < b，故选：B .
(2019•新课标 H)若a > b，则( )
A. In(a — b) > 0 B. 3a < 3b C. a3 — b3 > 0 D. I a l>l b I
【答案】C
【解析】取a = 0 , b = -1,则 In(a -b) = ln1 = 0，排除 A ；
3a = 30 = 1 > 3b = 3-1 =—,排除 B ； a 2 1
f (x)在(0,+8)上单调递减，f (2- 2) > f (2- 3) > f (log 3 4),故选：C .
4. (2019•天津)已知 a = log 2 , b = log , c = ,2，则 a , b , c 的大小关系为(
)
A. a < c < b B. a < b < c C. b < c < a D. c < a < b
【答案】A
= 03 > (—1)3 = —1 = b3，故 C 对；
3
I a I= 0 <I -1I = 1 = b，排除 D .故选：C .
(2019•新课标0)设f(x)是定义域为R的偶函数，且在(0,+8)单调递减，则( )
13 2 12 3
A. f (log -) > f (2-2) > f (2-3) B. f (log -) > f (2-3) > f (2-2)
34 34
3 _2 1 _ _2 _3 1
C. f (2-2) > f (2-3) > f (log -) D. f (2-3) > f (2-2) > f (log -)
34 34
【答案】C
【解析】• ；f(x)是定义域为R的偶函数，，f (log i) = f (log 4), 3 4 3
3 2 3
♦「log 4 >log 3 = 1, 0< 2-2 < 2-3 < 20 = 1,・., 0< 2-2