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

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

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

We multiply parentheses ..

(+27x^2+27x+81x+81)=0

We get rid of parentheses

27x^2+27x+81x+81=0

We add all the numbers together, and all the variables

27x^2+108x+81=0

a = 27; b = 108; c = +81;
Δ = b2-4ac
Δ = 1082-4·27·81
Δ = 2916
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2916}=54$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(108)-54}{2*27}=\frac{-162}{54}
=-3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(108)+54}{2*27}=\frac{-54}{54}
=-1
$