(3v+4)(9-v)=0

Solution for (3v+4)(9-v)=0 equation:

(3v+4)(9-v)=0

We add all the numbers together, and all the variables

(3v+4)(-1v+9)=0

We multiply parentheses ..

(-3v^2+27v-4v+36)=0

We get rid of parentheses

-3v^2+27v-4v+36=0

We add all the numbers together, and all the variables

-3v^2+23v+36=0

a = -3; b = 23; c = +36;
Δ = b2-4ac
Δ = 232-4·(-3)·36
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(23)-31}{2*-3}=\frac{-54}{-6}
=+9
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(23)+31}{2*-3}=\frac{8}{-6}
=-1+1/3
$