36k^2-80k-80=0

Solution for 36k^2-80k-80=0 equation:

36k^2-80k-80=0

a = 36; b = -80; c = -80;
Δ = b2-4ac
Δ = -802-4·36·(-80)
Δ = 17920
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{17920}=\sqrt{256*70}=\sqrt{256}*\sqrt{70}=16\sqrt{70}$
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-80)-16\sqrt{70}}{2*36}=\frac{80-16\sqrt{70}}{72}
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-80)+16\sqrt{70}}{2*36}=\frac{80+16\sqrt{70}}{72}
$