3x(x+6)=-18

Solution for 3x(x+6)=-18 equation:

3x(x+6)=-18

We move all terms to the left:

3x(x+6)-(-18)=0

We add all the numbers together, and all the variables

3x(x+6)+18=0

We multiply parentheses

3x^2+18x+18=0

a = 3; b = 18; c = +18;
Δ = b2-4ac
Δ = 182-4·3·18
Δ = 108
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:

$\sqrt{\Delta}=\sqrt{108}=\sqrt{36*3}=\sqrt{36}*\sqrt{3}=6\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-6\sqrt{3}}{2*3}=\frac{-18-6\sqrt{3}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+6\sqrt{3}}{2*3}=\frac{-18+6\sqrt{3}}{6}
$