Question

函数y=的反函数是(    )

A.y=                              B.y=

C.y=                              D.y=

Answer 1

A

解析：当x＜0时,由y=x²,得x=-.故反函数为y=f^-1(x)=-(x＞0).

当x≥0时,由y=-x,得x=-2y.

故反函数为y=f^-1(x)=-2x(x≤0).

∴y=f^-1(x)=-x,x＞0,

-2x,x≤0.