（x²-1分之x-3）÷（x²+2x+1分之x²-2x-3)-(x+1分之1）
=(x-3)/(x+1)(x-1)×(x+1)²/(x-3)(x+1)-1/(x+1)
=1/(x-1)-1/(x+1)
=(x+1-x+1)/(x²-1)
=2/(x²-1)O(∩_∩)O谢谢