Question

函数y=log₂(x+4)(x＞0)的反函数是(    )

A．y=2^x+4(x＞2)                                  B．y=2^x+4(x＞0)

C．y=2^x-4(x＞2)                                   D．y=2^x-4(x＞0)

Answer 1

答案：C

【解析】由x＞0可得y=log₂(x+4)＞2，且x=2^y-4，∴函数y=log₂(x+4)(x＞0)的反函数为y=2^x-4(x＞2)．