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

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

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

(-5v^2+7v+25v-35)=0

We get rid of parentheses

-5v^2+7v+25v-35=0

We add all the numbers together, and all the variables

-5v^2+32v-35=0

a = -5; b = 32; c = -35;
Δ = b2-4ac
Δ = 322-4·(-5)·(-35)
Δ = 324
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{324}=18$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(32)-18}{2*-5}=\frac{-50}{-10}
=+5
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(32)+18}{2*-5}=\frac{-14}{-10}
=1+2/5
$