题目

设f(x)=lnx,g(x)的反函数=2(x+1)/(x-1),则·f(g(x))

提问时间：2021-01-09

答案

y=g^-1(x)=2(x+1)/(x-1)
x(y-2)=y+2
x=(y+2)/(y-2)
xy互换
g(x)=(x+2)/(x-2)
f(g(x))=ln(x+2)/(x-2)
x>2或x