4x^2 . (-3x^4)=
(-3 y^2) . (-2 y^3)=
-xy . 3xy=
2xy . 5xy=
x . (-3x^3) . 2y=
-3x^5 . 4x . 2xy^2=
x^4 . 5x=
-6 x^4 y
-3x^2 y^2
6 y^5
-24 x^7 y^2
-12x^6
10 x^2 y^2
5x^5
