(x+y)^2-8(x^2-y^2)-16(x-y)^2
问题描述:
(x+y)^2-8(x^2-y^2)-16(x-y)^2
答
错了,是(x+y)^2-8(x^2-y^2)+16(x-y)^2
=[(x+y)-4(x-y)]^2
=(5y-3x)^2