3(x-9)(x+11)=0

Solution for 3(x-9)(x+11)=0 equation:

3(x-9)(x+11)=0

We multiply parentheses ..

3(+x^2+11x-9x-99)=0

We multiply parentheses

3x^2+33x-27x-297=0

We add all the numbers together, and all the variables

3x^2+6x-297=0

a = 3; b = 6; c = -297;
Δ = b2-4ac
Δ = 62-4·3·(-297)
Δ = 3600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3600}=60$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-60}{2*3}=\frac{-66}{6}
=-11
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+60}{2*3}=\frac{54}{6}
=9
$