-c^2-12c-20=0

Solution for -c^2-12c-20=0 equation:

-c^2-12c-20=0

We add all the numbers together, and all the variables

-1c^2-12c-20=0

a = -1; b = -12; c = -20;
Δ = b2-4ac
Δ = -122-4·(-1)·(-20)
Δ = 64
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{64}=8$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-8}{2*-1}=\frac{4}{-2}
=-2
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+8}{2*-1}=\frac{20}{-2}
=-10
$