-0.2x^2+1028x-28000=0

Solution for -0.2x^2+1028x-28000=0 equation:

-0.2x^2+1028x-28000=0

a = -0.2; b = 1028; c = -28000;
Δ = b2-4ac
Δ = 10282-4·(-0.2)·(-28000)
Δ = 1034384
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:

$\sqrt{\Delta}=\sqrt{1034384}=\sqrt{16*64649}=\sqrt{16}*\sqrt{64649}=4\sqrt{64649}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1028)-4\sqrt{64649}}{2*-0.2}=\frac{-1028-4\sqrt{64649}}{-0.4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1028)+4\sqrt{64649}}{2*-0.2}=\frac{-1028+4\sqrt{64649}}{-0.4}
$