1.163, -1.719

OK

A = 9
B = 5
C = -18

So, the quadratic formula is -5 +/- root(5^2-4*9*-18) all divided by 18 (2 * 9).

[-5 +/- root(25+648)] / 18.

[-5 +/- root(673)]/18.

The root of 673 is 25.942.

(-5 + 25.942) / 18 = 20.942/18 = 1.163

(-5 - 25.942) / 18 = -30.942/18 = -1.719

Just find where you're messing up and taking account of it. I think I'm clear enough with every step.