4x(3x+20)=360

Solution for 4x(3x+20)=360 equation:

4x(3x+20)=360

We move all terms to the left:

4x(3x+20)-(360)=0

We multiply parentheses

12x^2+80x-360=0

a = 12; b = 80; c = -360;
Δ = b2-4ac
Δ = 802-4·12·(-360)
Δ = 23680
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:

$\sqrt{\Delta}=\sqrt{23680}=\sqrt{64*370}=\sqrt{64}*\sqrt{370}=8\sqrt{370}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(80)-8\sqrt{370}}{2*12}=\frac{-80-8\sqrt{370}}{24}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(80)+8\sqrt{370}}{2*12}=\frac{-80+8\sqrt{370}}{24}
$