-20x^2-13x+15=0

Solution for -20x^2-13x+15=0 equation:

-20x^2-13x+15=0

a = -20; b = -13; c = +15;
Δ = b2-4ac
Δ = -132-4·(-20)·15
Δ = 1369
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1369}=37$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-37}{2*-20}=\frac{-24}{-40}
=3/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+37}{2*-20}=\frac{50}{-40}
=-1+1/4
$