Question

下列函数中最小值为4的函数是(    )

A.y=x+                                    B.y=sinx+(0＜x＜π)

C.y=2^x+4·2^-x                            D.y=log₃x+4log_x3

Answer 1

C

解析：y=2^x+4·2^-x≥2·=4.