15x^2-6x-216=0

Solution for 15x^2-6x-216=0 equation:

15x^2-6x-216=0

a = 15; b = -6; c = -216;
Δ = b2-4ac
Δ = -62-4·15·(-216)
Δ = 12996
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{12996}=114$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-114}{2*15}=\frac{-108}{30}
=-3+3/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+114}{2*15}=\frac{120}{30}
=4
$