(x^3-xy^2-x^2y+y^3) * (2x^3+y^3) = 2x^6+x^3y^3-2x^4y^2-xy^5-2x^5y-x^2y^4+2x^3y^3+y^6 = 2x^6+3x^3y^3-2x^4y^2-xy^5-2x^5y-x^2y^4+y^6