Question

下列函數(shù)中，有最小值的函數(shù)是（    ）

A.y=x+                                                 B.y=tanx+cotx

C.y=2^x+2^2-x                                            D.y=log₂x²+1

Answer 1

解析:x+≤-4或x+≥4,

tanx+cotx≤-2或tanx+cotx≥2,

log₂x²+1∈R,

2^x+2^2-x≥=4,

故選C.

答案:C