6*x的四次方+7*x的立方*y+5*x的平方*y的平方-x*y的三次方-2*y的四次方

6x^4+7x^3y+5x^2y^2-xy^3-2y^4
=6x^4+7x^3y+2x^2y^2+3x^2y^2-xy^3-2y^4
=x^2(6x^2+7xy+2y^2)+y^2(3x^2-xy-2y^2)
=x^2(2x+y)(3x+2y)+y^2(x-y)(3x+2y)
=(3x+2y)[x^2(2x+y)-y^2(x-y)].
=(3x+2y)(2x-y)(xy+x^2+y^2)