a²-1分之a²+3-【a-1分之a+1】+1
=（a²+3-(a+1)²+a²-1）/(a²-1)
=(a²+3-a²-2a-1+a²-1)/(a²-1)
=-1;
手机提问的朋友在客户端右上角评价点【满意】即可.
化简 a²-1分之a²+3-a-1分之a+1+1
a²-1分之a²+3-【a-1分之a+1】+1
=（a²+3-(a+1)²+a²-1）/(a²-1)
=(a²+3-a²-2a-1+a²-1)/(a²-1)
=-1;
手机提问的朋友在客户端右上角评价点【满意】即可.