Okay, I've got a bug in my calculations but this should work. I'll give you the general lay-out and let you fill in the rest. If you have questions just let us know.
First f(x) has to be a quadratic. The integrals are just constants so you will have \(\displaystyle a = \int_{-1}^0 f(x) ~ dx\) and similar for b and c. Thus \(\displaystyle f(x) = ax^2 + bx + c + 1\). Calculate these integrals out in terms of a, b, and c.
You will now have three equations in a, b, c. Solve the system and there you go.
-Dan