(a-b)²-(a-b)²等于多少

问题描述:

(a-b)²-(a-b)²等于多少
是(a+b)²-(a-b)²

(a-b)²-(a-b)²=0
(a+b)²-(a-b)²
=a²+2ab+b²-a²+2ab-b²
=4ab