(x+3)(2x)=360

Solution for (x+3)(2x)=360 equation:

(x+3)(2x)=360

We move all terms to the left:

(x+3)(2x)-(360)=0

We multiply parentheses

2x^2+6x-360=0

a = 2; b = 6; c = -360;
Δ = b2-4ac
Δ = 62-4·2·(-360)
Δ = 2916
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2916}=54$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-54}{2*2}=\frac{-60}{4}
=-15
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+54}{2*2}=\frac{48}{4}
=12
$