0=20x^2-13x-15

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

0=20x^2-13x-15

We move all terms to the left:

0-(20x^2-13x-15)=0

We add all the numbers together, and all the variables

-(20x^2-13x-15)=0

We get rid of parentheses

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