(2/1+a)-(a-2/a-1)÷(a²-2a/a²-2a+1)等于多少

2/1是二分之一嘛?
如果是的话
.(2/1+a)-(a-2/a-1)÷(a²-2a/a²-2a+1)
=（2/1+a-a+2/a+1）÷（a²-2/a-2a+1）
=[2/（1+a+2）×2]÷[(a²-2a+1）-2/a×2]
=（1+a+2）÷[2(a-1）²-a]
=（a+3）÷[2(a-1）²-a]
貌似就是酱紫了吧