(v-8)(5v+8)=0

Solution for (v-8)(5v+8)=0 equation:

(v-8)(5v+8)=0

We multiply parentheses ..

(+5v^2+8v-40v-64)=0

We get rid of parentheses

5v^2+8v-40v-64=0

We add all the numbers together, and all the variables

5v^2-32v-64=0

a = 5; b = -32; c = -64;
Δ = b2-4ac
Δ = -322-4·5·(-64)
Δ = 2304
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2304}=48$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-32)-48}{2*5}=\frac{-16}{10}
=-1+3/5
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-32)+48}{2*5}=\frac{80}{10}
=8
$