15x2-28x-36=0

Solution for 15x2-28x-36=0 equation:

15x^2-28x-36=0

a = 15; b = -28; c = -36;
Δ = b2-4ac
Δ = -282-4·15·(-36)
Δ = 2944
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{2944}=\sqrt{64*46}=\sqrt{64}*\sqrt{46}=8\sqrt{46}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-28)-8\sqrt{46}}{2*15}=\frac{28-8\sqrt{46}}{30}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-28)+8\sqrt{46}}{2*15}=\frac{28+8\sqrt{46}}{30}
$