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