(g+5)(7g+4)=0

Solution for (g+5)(7g+4)=0 equation:

(g+5)(7g+4)=0

We multiply parentheses ..

(+7g^2+4g+35g+20)=0

We get rid of parentheses

7g^2+4g+35g+20=0

We add all the numbers together, and all the variables

7g^2+39g+20=0

a = 7; b = 39; c = +20;
Δ = b2-4ac
Δ = 392-4·7·20
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$g_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$g_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$g_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(39)-31}{2*7}=\frac{-70}{14}
=-5
$
$g_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(39)+31}{2*7}=\frac{-8}{14}
=-4/7
$