x(x+9)=360

Solution for x(x+9)=360 equation:

x(x+9)=360

We move all terms to the left:

x(x+9)-(360)=0

We multiply parentheses

x^2+9x-360=0

a = 1; b = 9; c = -360;
Δ = b2-4ac
Δ = 92-4·1·(-360)
Δ = 1521
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1521}=39$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-39}{2*1}=\frac{-48}{2}
=-24
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+39}{2*1}=\frac{30}{2}
=15
$