8=4v^2-4v

Solution for 8=4v^2-4v equation:

8=4v^2-4v

We move all terms to the left:

8-(4v^2-4v)=0

We get rid of parentheses

-4v^2+4v+8=0

a = -4; b = 4; c = +8;
Δ = b2-4ac
Δ = 42-4·(-4)·8
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-12}{2*-4}=\frac{-16}{-8}
=+2
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+12}{2*-4}=\frac{8}{-8}
=-1
$