(9v+8)(v+7)=0

Solution for (9v+8)(v+7)=0 equation:

(9v+8)(v+7)=0

We multiply parentheses ..

(+9v^2+63v+8v+56)=0

We get rid of parentheses

9v^2+63v+8v+56=0

We add all the numbers together, and all the variables

9v^2+71v+56=0

a = 9; b = 71; c = +56;
Δ = b2-4ac
Δ = 712-4·9·56
Δ = 3025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3025}=55$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(71)-55}{2*9}=\frac{-126}{18}
=-7
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(71)+55}{2*9}=\frac{-16}{18}
=-8/9
$