(120+-23x+x^2)=0

Solution for (120+-23x+x^2)=0 equation:

(120+-23x+x^2)=0

We use the square of the difference formula

(120-23x+x^2)=0

We get rid of parentheses

x^2-23x+120=0

a = 1; b = -23; c = +120;
Δ = b2-4ac
Δ = -232-4·1·120
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-23)-7}{2*1}=\frac{16}{2}
=8
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-23)+7}{2*1}=\frac{30}{2}
=15
$