(4v+5)(9+v)=0

Solution for (4v+5)(9+v)=0 equation:

(4v+5)(9+v)=0

We add all the numbers together, and all the variables

(4v+5)(v+9)=0

We multiply parentheses ..

(+4v^2+36v+5v+45)=0

We get rid of parentheses

4v^2+36v+5v+45=0

We add all the numbers together, and all the variables

4v^2+41v+45=0

a = 4; b = 41; c = +45;
Δ = b2-4ac
Δ = 412-4·4·45
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{-(41)-31}{2*4}=\frac{-72}{8}
=-9
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(41)+31}{2*4}=\frac{-10}{8}
=-1+1/4
$