k^2=60-20k

Solution for k^2=60-20k equation:

k^2=60-20k

We move all terms to the left:

k^2-(60-20k)=0

We add all the numbers together, and all the variables

k^2-(-20k+60)=0

We get rid of parentheses

k^2+20k-60=0

a = 1; b = 20; c = -60;
Δ = b2-4ac
Δ = 202-4·1·(-60)
Δ = 640
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:

$\sqrt{\Delta}=\sqrt{640}=\sqrt{64*10}=\sqrt{64}*\sqrt{10}=8\sqrt{10}$
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-8\sqrt{10}}{2*1}=\frac{-20-8\sqrt{10}}{2}
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+8\sqrt{10}}{2*1}=\frac{-20+8\sqrt{10}}{2}
$