7(v-3)(v+6)=0

Solution for 7(v-3)(v+6)=0 equation:

7(v-3)(v+6)=0

We multiply parentheses ..

7(+v^2+6v-3v-18)=0

We multiply parentheses

7v^2+42v-21v-126=0

We add all the numbers together, and all the variables

7v^2+21v-126=0

a = 7; b = 21; c = -126;
Δ = b2-4ac
Δ = 212-4·7·(-126)
Δ = 3969
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3969}=63$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(21)-63}{2*7}=\frac{-84}{14}
=-6
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(21)+63}{2*7}=\frac{42}{14}
=3
$