(8+v)(5v+7)=0

Solution for (8+v)(5v+7)=0 equation:

(8+v)(5v+7)=0

We add all the numbers together, and all the variables

(v+8)(5v+7)=0

We multiply parentheses ..

(+5v^2+7v+40v+56)=0

We get rid of parentheses

5v^2+7v+40v+56=0

We add all the numbers together, and all the variables

5v^2+47v+56=0

a = 5; b = 47; c = +56;
Δ = b2-4ac
Δ = 472-4·5·56
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{-(47)-33}{2*5}=\frac{-80}{10}
=-8
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(47)+33}{2*5}=\frac{-14}{10}
=-1+2/5
$