13x^2-13x-390=0

Solution for 13x^2-13x-390=0 equation:

13x^2-13x-390=0

a = 13; b = -13; c = -390;
Δ = b2-4ac
Δ = -132-4·13·(-390)
Δ = 20449
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{20449}=143$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-143}{2*13}=\frac{-130}{26}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+143}{2*13}=\frac{156}{26}
=6
$