(x+9)(x-9)-144=0

Solution for (x+9)(x-9)-144=0 equation:

Simplifying
(x + 9)(x + -9) + -144 = 0

Reorder the terms:
(9 + x)(x + -9) + -144 = 0

Reorder the terms:
(9 + x)(-9 + x) + -144 = 0

Multiply (9 + x) * (-9 + x)
(9(-9 + x) + x(-9 + x)) + -144 = 0
((-9 * 9 + x * 9) + x(-9 + x)) + -144 = 0
((-81 + 9x) + x(-9 + x)) + -144 = 0
(-81 + 9x + (-9 * x + x * x)) + -144 = 0
(-81 + 9x + (-9x + x2)) + -144 = 0

Combine like terms: 9x + -9x = 0
(-81 + 0 + x2) + -144 = 0
(-81 + x2) + -144 = 0

Reorder the terms:
-81 + -144 + x2 = 0

Combine like terms: -81 + -144 = -225
-225 + x2 = 0

Solving
-225 + x2 = 0

Solving for variable 'x'.

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

Add '225' to each side of the equation.
-225 + 225 + x2 = 0 + 225

Combine like terms: -225 + 225 = 0
0 + x2 = 0 + 225
x2 = 0 + 225

Combine like terms: 0 + 225 = 225
x2 = 225

Simplifying
x2 = 225

Take the square root of each side:
x = {-15, 15}