That should be it since sqrt(17) is not a perfect square so you get -3±√(17)/2, because you cannot cancel anything out, as your answer. Just by looking at the discriminate , in this case 17, you can determine that the roots of your equation will be real,unequal and irrational, also it has two x-intercepts if you are graphing it.( For future reference)
Derivation of the quadratic formula:
Subtract both sides by c.
Divide through by a.
Complete the square on the left side (to keep equation balanced, add the new term to the right side as well)
The left side becomes a perfect square. Combine the terms on the right side of the equation:
Take the square root of both sides:
Solve for x: