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

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

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

We add all the numbers together, and all the variables

(-1v+7)(5v-8)=0

We multiply parentheses ..

(-5v^2+8v+35v-56)=0

We get rid of parentheses

-5v^2+8v+35v-56=0

We add all the numbers together, and all the variables

-5v^2+43v-56=0

a = -5; b = 43; c = -56;
Δ = b2-4ac
Δ = 432-4·(-5)·(-56)
Δ = 729
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{729}=27$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(43)-27}{2*-5}=\frac{-70}{-10}
=+7
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(43)+27}{2*-5}=\frac{-16}{-10}
=1+3/5
$