25(x-2y)的平方-4(y-2x)的平方急

问题描述:

25(x-2y)的平方-4(y-2x)的平方

(5x-10y)²-(4x-2y)²
=(5x-10y+4x-2y)(5x-10y-4x+2y)
=(9x-12y)(x-8y)
=3(3x-4y)(x-8y)