Answer:
3x^3+7x^2y−4y^3
Step-by-step explanation:
(3x^2+xy+−2y^2)(x+2y)
=(3x^2)(x)+(3x^2)(2y)+(xy)(x)+(xy)(2y)+(−2y^2)(x)+(−2y^2)(2y)
=3x^3+6x^2y+x2y+2xy^−2xy^2−4y^3
=3x^3+7x^2y−4y^3
