When in doubt use the quadratic formula. (We don't really need to here, but if you run out of other ideas then this ALWAYS works.)
A quick note: Whenever you solve a quadratic you will get one of the three possibilities:
1) Two unequal real roots
2) One real root (actually two identical real roots)
3) Two complex roots (they will be complex conjugates of each other.)
I'm not sure why you are having a problem graphing. All you need to do is pick some x value and plug it into:
and the corresponding y value comes out.