化简:(x-y)(x-2y)+(x+2y)(x-3y)

化简:(x-y)(x-2y)+(x+2y)(x-3y)
化简:(x-y)(x-2y)+(x+2y)(x-3y)

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.

拆开就行了啊
(x-y)(x-2y)+(x+2y)(x-3y)
= xx-3xy+2yy + xx-xy-6yy
= 2xx - 4xy - 4yy
= 2(xx - 2xy - 2yy)