3(v-1)(-v-7)=0

Solution for 3(v-1)(-v-7)=0 equation:

3(v-1)(-v-7)=0

We add all the numbers together, and all the variables

3(v-1)(-1v-7)=0

We multiply parentheses ..

3(-1v^2-7v+v+7)=0

We multiply parentheses

-3v^2-21v+3v+21=0

We add all the numbers together, and all the variables

-3v^2-18v+21=0

a = -3; b = -18; c = +21;
Δ = b2-4ac
Δ = -182-4·(-3)·21
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-18)-24}{2*-3}=\frac{-6}{-6}
=1
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-18)+24}{2*-3}=\frac{42}{-6}
=-7
$