This qn is quite tedious to do, but can be done. You have to use the portion that is given and convert it to form the "sum". Then, use part of the induction method to find the general term of the sum of 10r^4 + 2r^2. So after you managed to get that, u have to use the equation for the sum of r^2 and substitute it into the eqn to get the general equation.