-4x^2×(二分之一xy-y^2)-3x×(xy^2-2x^2y)

问题描述:

-4x^2×(二分之一xy-y^2)-3x×(xy^2-2x^2y)

=-2x^3y+4x^2y^2-3x^2y^2+6x^3y
=4x^3y+x^2y^2