计算(x-2y+4)(x+2y-4)
问题描述:
计算(x-2y+4)(x+2y-4)
答
(x-2y+4)(x+2y-4)
=(x-(2y-4))(x+2y-4)
=x^2-(2y-4)^2
=x^2-4y^2+16y-16