80=v(2)+0.5(40)

Solution for 80=v(2)+0.5(40) equation:

80=v(2)+0.5(40)

We move all terms to the left:

80-(v(2)+0.5(40))=0

We add all the numbers together, and all the variables

-(+v^2+0.540)+80=0

We get rid of parentheses

-v^2-0.540+80=0

We add all the numbers together, and all the variables

-1v^2+79.46=0

a = -1; b = 0; c = +79.46;
Δ = b2-4ac
Δ = 02-4·(-1)·79.46
Δ = 317.84
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-\sqrt{317.84}}{2*-1}=\frac{0-\sqrt{317.84}}{-2}
=-\frac{\sqrt{}}{-2}
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{317.84}}{2*-1}=\frac{0+\sqrt{317.84}}{-2}
=\frac{\sqrt{}}{-2}
$