(9+x)(3x+4)=0

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

(9+x)(3x+4)=0

We add all the numbers together, and all the variables

(x+9)(3x+4)=0

We multiply parentheses ..

(+3x^2+4x+27x+36)=0

We get rid of parentheses

3x^2+4x+27x+36=0

We add all the numbers together, and all the variables

3x^2+31x+36=0

a = 3; b = 31; c = +36;
Δ = b2-4ac
Δ = 312-4·3·36
Δ = 529
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{529}=23$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(31)-23}{2*3}=\frac{-54}{6}
=-9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(31)+23}{2*3}=\frac{-8}{6}
=-1+1/3
$