d^2+6d=-6

Solution for d^2+6d=-6 equation:

d^2+6d=-6

We move all terms to the left:

d^2+6d-(-6)=0

We add all the numbers together, and all the variables

d^2+6d+6=0

a = 1; b = 6; c = +6;
Δ = b2-4ac
Δ = 62-4·1·6
Δ = 12
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{12}=\sqrt{4*3}=\sqrt{4}*\sqrt{3}=2\sqrt{3}$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-2\sqrt{3}}{2*1}=\frac{-6-2\sqrt{3}}{2}
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+2\sqrt{3}}{2*1}=\frac{-6+2\sqrt{3}}{2}
$