计算:(x+3y)2-2(x+3y)(x-3y)+(x-3y)2.

问题描述:

计算:(x+3y)2-2(x+3y)(x-3y)+(x-3y)2

原式=[(x+3y)-(x-3y)]2
=(x+3y-x+3y)2
=36y2