-8x^2-20x-8=0

Solution for -8x^2-20x-8=0 equation:

-8x^2-20x-8=0

a = -8; b = -20; c = -8;
Δ = b2-4ac
Δ = -202-4·(-8)·(-8)
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-12}{2*-8}=\frac{8}{-16}
=-1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+12}{2*-8}=\frac{32}{-16}
=-2
$