15x^2-57x-12=0

Solution for 15x^2-57x-12=0 equation:

15x^2-57x-12=0

a = 15; b = -57; c = -12;
Δ = b2-4ac
Δ = -572-4·15·(-12)
Δ = 3969
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3969}=63$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-57)-63}{2*15}=\frac{-6}{30}
=-1/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-57)+63}{2*15}=\frac{120}{30}
=4
$