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

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

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

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

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

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

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

Solving
-81 + x2 = 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 + x2 = 0 + 81

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

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

Simplifying
x2 = 81

Take the square root of each side:
x = {-9, 9}