(a+b)(a-b)-(a-b)的二次方+2b的二次方

问题描述:

(a+b)(a-b)-(a-b)的二次方+2b的二次方

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