Simplify: (a2−b2)+2b2(a^2 - b^2) + 2b^2(a2−b2)+2b2.
a2+b2a^2 + b^2a2+b2
a2−b2a^2 - b^2a2−b2
a2−3b2a^2 - 3b^2a2−3b2
2a2−b22a^2 - b^22a2−b2