设函数f(x)=2|x|,则下列结论中正确的是( )(A)f(-1)<f(2)<f(-)(B)f...
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问题详情：
设函数f(x)=2|x|,则下列结论中正确的是( )
(A)f(-1)<f(2)<f(-)
(B)f(-)<f(-1)<f(2)
(C)f(2)<f(-)<f(-1)
(D)f(-1)<f(-)<f(2)
【回答】
D解析:由题意,f(x)=2|x|=2|-x|=f(-x),
即f(x)为偶函数.
故
显然x≥0时,f(x)=2x单调递增.
所以f(1)<f()<f(2),
即f(-1)<f(-)<f(2).
知识点：基本初等函数I
题型：选择题
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