令y=f(x)=(2x-1)/(1-x)
那么y(1-x)=2x-1
y-yx=2x-1
(2+y)x=y+1
所以x=(y+1)/(y+2) (y≠-2)
x、y互换得：y=(x+1)/(x+2) (x≠-2)