15x2-57x-90=0

Solution for 15x2-57x-90=0 equation:

15x^2-57x-90=0

a = 15; b = -57; c = -90;
Δ = b2-4ac
Δ = -572-4·15·(-90)
Δ = 8649
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{8649}=93$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-57)-93}{2*15}=\frac{-36}{30}
=-1+1/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-57)+93}{2*15}=\frac{150}{30}
=5
$