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