x/(x-1) =2/(x平方-1) +2 两边乘(x+1)(x-1)
x(x+1)=2+2(x+1)(x-1)
x^2+x=2+2x^2-2
2x^2-x^2-x=0
x^2-x=0
x(x-1)=0
x=0 x=1()舍