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

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

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

Reorder the terms:
(-9 + 3x)(3x + 9) = 0

Reorder the terms:
(-9 + 3x)(9 + 3x) = 0

Multiply (-9 + 3x) * (9 + 3x)
(-9(9 + 3x) + 3x * (9 + 3x)) = 0
((9 * -9 + 3x * -9) + 3x * (9 + 3x)) = 0
((-81 + -27x) + 3x * (9 + 3x)) = 0
(-81 + -27x + (9 * 3x + 3x * 3x)) = 0
(-81 + -27x + (27x + 9x2)) = 0

Combine like terms: -27x + 27x = 0
(-81 + 0 + 9x2) = 0
(-81 + 9x2) = 0

Solving
-81 + 9x2 = 0

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '81' to each side of the equation.
-81 + 81 + 9x2 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + 9x2 = 0 + 81
9x2 = 0 + 81

Combine like terms: 0 + 81 = 81
9x2 = 81

Divide each side by '9'.
x2 = 9

Simplifying
x2 = 9

Take the square root of each side:
x = {-3, 3}