设y=g(x),z=f(x)
则y=1+z所以z=y-1
x=g-1(y)
x=f-1(z)
所以x=g-1(y)=f-1(z),=f-1(y-1)
即 g-1(y)=f-1(y-1)
所以 g-1(x)=f-1(x-1)