原式=
(1/(x-1))+(2x/(1-x^2))
(1/(x-1))在分式上下同乘(x+1),即用分式的基本性质
得:
((x+1)/(x^2-1))+(2x/(1-x^2))
(2x/(1-x^2))在分式上下同乘(-1),即用分式的基本性质
得:
(x+1-2x)/(x^2-1)
=(1-x)/(x+1)(x-1) (逆用平方差公式)
= -(x-1)/(x+1)(x-1)
在分式上下同除(x-1),即用分式的基本性质
得:
=(-1)/(x+1)
答:为(-1)/(x+1)