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

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

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

(+5v^2+25v-8v-40)=0

We get rid of parentheses

5v^2+25v-8v-40=0

We add all the numbers together, and all the variables

5v^2+17v-40=0

a = 5; b = 17; c = -40;
Δ = b2-4ac
Δ = 172-4·5·(-40)
Δ = 1089
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1089}=33$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(17)-33}{2*5}=\frac{-50}{10}
=-5
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(17)+33}{2*5}=\frac{16}{10}
=1+3/5
$