Using an upper-case "C" for any arbitrary constants, find the general indefinite integral

Question

∫ (-2-t)(-9-t^2) dt

Now I multiplied both parentheses to get:

∫ (18 + 2t^2 + 9t + t^3) dt

now I integrated and got:

18t + 2t^3/3 + 9t^2/2 + t^4/4 + C

but I'm told this answer is incorrect.
What am I doing wrong?

Thank you

Answer 1

I have
(t^2 + 9)(t+2)
is
t^3 + 2 t^2 + 9 t + 18

t^4/4 + (2/3) t^3 + (9/2) t^2 + 18 t + C

I agree with you.

Answer 2

okay so there must be a mistake with the system, thanks for clearing that up Damon.