-2x^2+120x-800=0

Solution for -2x^2+120x-800=0 equation:

-2x^2+120x-800=0

a = -2; b = 120; c = -800;
Δ = b2-4ac
Δ = 1202-4·(-2)·(-800)
Δ = 8000
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:

$\sqrt{\Delta}=\sqrt{8000}=\sqrt{1600*5}=\sqrt{1600}*\sqrt{5}=40\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(120)-40\sqrt{5}}{2*-2}=\frac{-120-40\sqrt{5}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(120)+40\sqrt{5}}{2*-2}=\frac{-120+40\sqrt{5}}{-4}
$