-5x^2-30x+80=0

Solution for -5x^2-30x+80=0 equation:

-5x^2-30x+80=0

a = -5; b = -30; c = +80;
Δ = b2-4ac
Δ = -302-4·(-5)·80
Δ = 2500
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2500}=50$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-50}{2*-5}=\frac{-20}{-10}
=+2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+50}{2*-5}=\frac{80}{-10}
=-8
$