-3v^2-6v=-81

Solution for -3v^2-6v=-81 equation:

-3v^2-6v=-81

We move all terms to the left:

-3v^2-6v-(-81)=0

We add all the numbers together, and all the variables

-3v^2-6v+81=0

a = -3; b = -6; c = +81;
Δ = b2-4ac
Δ = -62-4·(-3)·81
Δ = 1008
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1008}=\sqrt{144*7}=\sqrt{144}*\sqrt{7}=12\sqrt{7}$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-12\sqrt{7}}{2*-3}=\frac{6-12\sqrt{7}}{-6}
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+12\sqrt{7}}{2*-3}=\frac{6+12\sqrt{7}}{-6}
$