0=2s^2-13s-15

Solution for 0=2s^2-13s-15 equation:

0=2s^2-13s-15

We move all terms to the left:

0-(2s^2-13s-15)=0

We add all the numbers together, and all the variables

-(2s^2-13s-15)=0

We get rid of parentheses

-2s^2+13s+15=0

a = -2; b = 13; c = +15;
Δ = b2-4ac
Δ = 132-4·(-2)·15
Δ = 289
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{289}=17$
$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(13)-17}{2*-2}=\frac{-30}{-4}
=7+1/2
$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(13)+17}{2*-2}=\frac{4}{-4}
=-1
$