Simplify: a2+2a+3a2−aa^2 + 2a + 3a^2 - aa2+2a+3a2−a.
4a2+a4a^2 + a4a2+a
5a25a^25a2
4a2−a4a^2 - a4a2−a
3a2+3a3a^2 + 3a3a2+3a