1.x+1分之x-1减去x²-1分之4=x+1分之x+2
(x-1)/(x+1) - 4/(x²-1)=(x+2)/(x+1)
同时乘以x²-1得
(x-1)²-4=(x+2)(x-1)
整理得
x²-2x-3=x²+x-2
解得x=-1/3