You could try to 1. parse all and 2. transform it into a Horner scheme.

The second step would imply multiplying all parts out especially the parens and summing up all parts where x has the same power.

At the end you should have something of the form of a sum 0 = a + bx + cx² + dx³ + ...

(I suppose you don't expect any exponents bigger or equal 2, but the approach is the same)

Already the first parsing step isn't easy and since you didn't provide any code I dare to doubt that you could master to understand the full algorithm.

So better try doing your homework or just acquire a symbolic calculator. ;-)

HTH! :)