15x^2-72x-108=0

Solution for 15x^2-72x-108=0 equation:

15x^2-72x-108=0

a = 15; b = -72; c = -108;
Δ = b2-4ac
Δ = -722-4·15·(-108)
Δ = 11664
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{11664}=108$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-72)-108}{2*15}=\frac{-36}{30}
=-1+1/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-72)+108}{2*15}=\frac{180}{30}
=6
$