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

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

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

We multiply parentheses ..

(+35v^2+40v+56v+64)=0

We get rid of parentheses

35v^2+40v+56v+64=0

We add all the numbers together, and all the variables

35v^2+96v+64=0

a = 35; b = 96; c = +64;
Δ = b2-4ac
Δ = 962-4·35·64
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(96)-16}{2*35}=\frac{-112}{70}
=-1+3/5
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(96)+16}{2*35}=\frac{-80}{70}
=-1+1/7
$