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

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

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

We move all terms to the left:

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


We calculate terms in parentheses: +(3x-9)(3x+9-()), so:

3x-9)(3x+9-()

We add all the numbers together, and all the variables

3x-9)(3x

Back to the equation:

+(3x-9)(3x)


We multiply parentheses

9x^2-27x=0

a = 9; b = -27; c = 0;
Δ = b2-4ac
Δ = -272-4·9·0
Δ = 729
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{729}=27$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-27)-27}{2*9}=\frac{0}{18}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-27)+27}{2*9}=\frac{54}{18}
=3
$