3x(x+6)=480

Solution for 3x(x+6)=480 equation:

3x(x+6)=480

We move all terms to the left:

3x(x+6)-(480)=0

We multiply parentheses

3x^2+18x-480=0

a = 3; b = 18; c = -480;
Δ = b2-4ac
Δ = 182-4·3·(-480)
Δ = 6084
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6084}=78$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-78}{2*3}=\frac{-96}{6}
=-16
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+78}{2*3}=\frac{60}{6}
=10
$