-36k^2-20k=0

Solution for -36k^2-20k=0 equation:

-36k^2-20k=0

a = -36; b = -20; c = 0;
Δ = b2-4ac
Δ = -202-4·(-36)·0
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-20}{2*-36}=\frac{0}{-72}
=0
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+20}{2*-36}=\frac{40}{-72}
=-5/9
$