x^2+13x-660=0

Solution for x^2+13x-660=0 equation:

x^2+13x-660=0

a = 1; b = 13; c = -660;
Δ = b2-4ac
Δ = 132-4·1·(-660)
Δ = 2809
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2809}=53$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(13)-53}{2*1}=\frac{-66}{2}
=-33
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(13)+53}{2*1}=\frac{40}{2}
=20
$