x(x+3)=9(9+9)

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

x(x+3)=9(9+9)

We move all terms to the left:

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

We add all the numbers together, and all the variables

x(x+3)-(918)=0

We add all the numbers together, and all the variables

x(x+3)-918=0

We multiply parentheses

x^2+3x-918=0

a = 1; b = 3; c = -918;
Δ = b2-4ac
Δ = 32-4·1·(-918)
Δ = 3681
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{3681}=\sqrt{9*409}=\sqrt{9}*\sqrt{409}=3\sqrt{409}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(3)-3\sqrt{409}}{2*1}=\frac{-3-3\sqrt{409}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+3\sqrt{409}}{2*1}=\frac{-3+3\sqrt{409}}{2}
$