Let

Then we need to solve

The rational root theorem says that if there is a rational root for this polynomial equation it is of the form .

Trial and error shows that y = -1/2 is indeed a solution. This means we can draw out a factor of the form 2y + 1:

by any method of polynomial division you choose.

So finishing the solution I get that

So we need to solve for the three solutions:

and

and

The last two are impossible, as . So we only have

-Dan