3x(X+12)=12

Solution for 3x(X+12)=12 equation:

3x(x+12)=12

We move all terms to the left:

3x(x+12)-(12)=0

We multiply parentheses

3x^2+36x-12=0

a = 3; b = 36; c = -12;
Δ = b2-4ac
Δ = 362-4·3·(-12)
Δ = 1440
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:

$\sqrt{\Delta}=\sqrt{1440}=\sqrt{144*10}=\sqrt{144}*\sqrt{10}=12\sqrt{10}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(36)-12\sqrt{10}}{2*3}=\frac{-36-12\sqrt{10}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(36)+12\sqrt{10}}{2*3}=\frac{-36+12\sqrt{10}}{6}
$