-5x^2+86x+72=0

Solution for -5x^2+86x+72=0 equation:

-5x^2+86x+72=0

a = -5; b = 86; c = +72;
Δ = b2-4ac
Δ = 862-4·(-5)·72
Δ = 8836
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{8836}=94$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(86)-94}{2*-5}=\frac{-180}{-10}
=+18
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(86)+94}{2*-5}=\frac{8}{-10}
=-4/5
$