x^2-xy-2y^2+x+7y-6
问题描述：
x^2-xy-2y^2+x+7y-6
答
x^2+xy-2y^2-x+7y-6
=(x^2-xy+2x)+(2xy-2y^2+4y)-(3x-3y+6)
=x(x-y+2)+2y(x-y+2)-3(x-y+2)
=(x-y+2)(x+2y-3)
题写错啦,