设f(x)=1/x,则f[f(x)]=( ) (A)1/x (B)1/xˆ2 (C)x (D)xˆ2

问题描述:

设f(x)=1/x,则f[f(x)]=( ) (A)1/x (B)1/xˆ2 (C)x (D)xˆ2

C
f(x)=t =1/x 则 f[f(x)]=f[t] =1/t=1/1/x=x