0=-x^2+240x-4150

Solution for 0=-x^2+240x-4150 equation:

0=-x^2+240x-4150

We move all terms to the left:

0-(-x^2+240x-4150)=0

We add all the numbers together, and all the variables

-(-x^2+240x-4150)=0

We get rid of parentheses

x^2-240x+4150=0

a = 1; b = -240; c = +4150;
Δ = b2-4ac
Δ = -2402-4·1·4150
Δ = 41000
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:

$\sqrt{\Delta}=\sqrt{41000}=\sqrt{100*410}=\sqrt{100}*\sqrt{410}=10\sqrt{410}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-240)-10\sqrt{410}}{2*1}=\frac{240-10\sqrt{410}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-240)+10\sqrt{410}}{2*1}=\frac{240+10\sqrt{410}}{2}
$