(8v+9)(5v+9)=0

Solution for (8v+9)(5v+9)=0 equation:

(8v+9)(5v+9)=0

We multiply parentheses ..

(+40v^2+72v+45v+81)=0

We get rid of parentheses

40v^2+72v+45v+81=0

We add all the numbers together, and all the variables

40v^2+117v+81=0

a = 40; b = 117; c = +81;
Δ = b2-4ac
Δ = 1172-4·40·81
Δ = 729
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{729}=27$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(117)-27}{2*40}=\frac{-144}{80}
=-1+4/5
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(117)+27}{2*40}=\frac{-90}{80}
=-1+1/8
$