-5x^2-40X+100=0

Solution for -5x^2-40X+100=0 equation:

-5x^2-40x+100=0

a = -5; b = -40; c = +100;
Δ = b2-4ac
Δ = -402-4·(-5)·100
Δ = 3600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3600}=60$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-40)-60}{2*-5}=\frac{-20}{-10}
=+2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+60}{2*-5}=\frac{100}{-10}
=-10
$