0=v2-2v-80

Solution for 0=v2-2v-80 equation:

0=v2-2v-80

We move all terms to the left:

0-(v2-2v-80)=0

We add all the numbers together, and all the variables

-(+v^2-2v-80)+0=0

We add all the numbers together, and all the variables

-(+v^2-2v-80)=0

We get rid of parentheses

-v^2+2v+80=0

We add all the numbers together, and all the variables

-1v^2+2v+80=0

a = -1; b = 2; c = +80;
Δ = b2-4ac
Δ = 22-4·(-1)·80
Δ = 324
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{324}=18$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-18}{2*-1}=\frac{-20}{-2}
=+10
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+18}{2*-1}=\frac{16}{-2}
=-8
$