1. ## Binomial theorem expansion.

Use the binomial theorem to expand (3x-2y^2)^4

-6x^5 - 30x^4y^2 - 60x^3y^4 - 60x^2y^4 - 30xy^8 -6y^10

I think this is right.
Does any one mind checking my answer? Thank you!

2. $(3x-2y^2)^4=(3x)^4-C_4^1(3x)^3(2y^2)+C_4^2(3x)^2(2y^2)^2-C_4^3(3x)(2y^2)^3+(2y^2)^4=$

$=81x^4-216x^3y^2+144x^2y^4-96xy^6+16y^8$