化简,亲快啊啊急!(3x-2y)(7x-y)-(4x+3y)(x-y)

问题描述:

化简,亲快啊啊急!(3x-2y)(7x-y)-(4x+3y)(x-y)

=21x^2-3xy-14xy+2y^2-(4x^2-4xy+3xy-3y^2)
=21x^2-17xy+2y^2-4x^2+xy+3y^2
=17x^2-16xy+5y^2