How do you work x2-x-18?

Answer 1

I'm guessing that you have a quadratic equation and you're looking for the roots (where it's equal to 0). Since x² - x - 18 isn't foing to factor nicely, use the quadratic formula for ax² + bx + c = 0
x = (-b ± √(b² - 4ac))/2a with
a = 1
b = -1
c = -18 (from your original equation) and
x = (1 ± √(1 + 72))/2 = (1 ± √(73))/2
x = .5 ± 4.272 so the roots are
x = 4.772 and x = -3.772

HTH

Doug