化简 ( 1÷a-b-1÷a+b )÷ab÷a²-b²

题目

化简 ( 1÷a-b-1÷a+b )÷ab÷a²-b²
化简 ( 1÷a-b)-(1÷a+b )÷ab÷a²-b²

答案

是这个吗
[1/(a-b)-1/(a+b)]÷(ab/(a²-b²))
=(a+b-a+b)/[(a+b)(a-b)]÷ab/[(a+b)(a-b)]
=2b/ab
=2/a (即2÷a)