-864=-6d2

Solution for -864=-6d2 equation:

-864=-6d^2

We move all terms to the left:

-864-(-6d^2)=0

We get rid of parentheses

6d^2-864=0

a = 6; b = 0; c = -864;
Δ = b2-4ac
Δ = 02-4·6·(-864)
Δ = 20736
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{20736}=144$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-144}{2*6}=\frac{-144}{12}
=-12
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+144}{2*6}=\frac{144}{12}
=12
$