题目

约分,(x-y)(a-b)/(x^2-y^2)(b-a)

提问时间：2021-03-20

答案

(x-y)(a-b)
___________
(x2-y2)(b-a)
=-(x-y)(b-a)
___________
(x-y)(x+y)(b-a)
= -1
____
(x+y)