= 2a^2(a^2+2ab+5b^2) - 3b(a^2+2ab+5b^2)= 2a^4 + 4a^3b + 10a^2b^2 - 3a^2b - 6ab^2 - 15b^3= 2a^4 + 4a^3b + 10a^2b^2 - 3a^2b - 6ab^2 - 15b^3
= 2a^2(a^2+2ab+5b^2) - 3b(a^2+2ab+5b^2)
= 2a^4 + 4a^3b + 10a^2b^2 - 3a^2b - 6ab^2 - 15b^3
= 2a^4 + 4a^3b + 10a^2b^2 - 3a^2b - 6ab^2 - 15b^3