[(a+2b)^2+(a-2b)^2](a^2-ab^2)
=2(a^2+4b^2)(a^2-ab^2)
=2(a^4+a^3b^2+4a^2b^2-4ab^4)化简全了是？是=2ab(a^3+a^2b^2+4ab-4b^3)