(x+2y)(x-y)(x-2y)(x+y) 计算 急

问题描述:

(x+2y)(x-y)(x-2y)(x+y) 计算 急

原式=[(x+2y)(x-2y)][(x-y)(x+y)]
=(x²-4y²)(x²-y²)
=x⁴-5x²y²+4y⁴