-0.2x^2-100x-2500=0

Solution for -0.2x^2-100x-2500=0 equation:

-0.2x^2-100x-2500=0

a = -0.2; b = -100; c = -2500;
Δ = b2-4ac
Δ = -1002-4·(-0.2)·(-2500)
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{-(-100)-40\sqrt{5}}{2*-0.2}=\frac{100-40\sqrt{5}}{-0.4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-100)+40\sqrt{5}}{2*-0.2}=\frac{100+40\sqrt{5}}{-0.4}
$