Simplify: (a+b)3−(a−b)3b\frac{(a+b)^3 - (a-b)^3}{b}b(a+b)3−(a−b)3 (assume b≠0b \neq 0b=0).
6a2+2b26a^2 + 2b^26a2+2b2
6ab6ab6ab
2b22b^22b2
6a26a^26a2