Add polynomials

simplify:

(-5a^3 - 2a^2) + (6a^3+9a^2+8a)

If you would like to calculate (-5a^3 - 2a^2) + (6a^3 + 9a^2 + 8a), you can do this using the following steps:

(-5a^3 - 2a^2) + (6a^3 + 9a^2 + 8a) = -5a^3 - 2a^2 + 6a^3 + 9a^2 + 8a = a^3 + 7a^2 + 8a

The correct result would be a^3 + 7a^2 + 8a.