化简:(x-y)(x-2y)+(x+2y)(x-3y)

问题描述:

化简:(x-y)(x-2y)+(x+2y)(x-3y)

(x-y)(x-2y)+(x+2y)(x-3y)
=x^2-2xy-xy+2y^2+x^2-3xy+2xy-6y^2
=2x^2-4xy-4y^2.