(x+2y)(3x-7y)2-4(x+y)2(x+2y)

问题描述:

(x+2y)(3x-7y)2-4(x+y)2(x+2y)

原式=(x+2y)[(3x-7y)2-4(x+y)2]
=(x+2y)[(3x-7y)+2(x+y)][(3x-7y)-2(x+y)]
=(x+2y)(5x-5y)(x-9y)
=5(x+2y)(x-y)(x-9y).