x^2-120x+300=0

Solution for x^2-120x+300=0 equation:

x^2-120x+300=0

a = 1; b = -120; c = +300;
Δ = b2-4ac
Δ = -1202-4·1·300
Δ = 13200
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{13200}=\sqrt{400*33}=\sqrt{400}*\sqrt{33}=20\sqrt{33}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-120)-20\sqrt{33}}{2*1}=\frac{120-20\sqrt{33}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-120)+20\sqrt{33}}{2*1}=\frac{120+20\sqrt{33}}{2}
$