(n+9)(n-9)=0

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

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

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

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

Multiply (9 + n) * (-9 + n)
(9(-9 + n) + n(-9 + n)) = 0
((-9 * 9 + n * 9) + n(-9 + n)) = 0
((-81 + 9n) + n(-9 + n)) = 0
(-81 + 9n + (-9 * n + n * n)) = 0
(-81 + 9n + (-9n + n2)) = 0

Combine like terms: 9n + -9n = 0
(-81 + 0 + n2) = 0
(-81 + n2) = 0

Solving
-81 + n2 = 0

Solving for variable 'n'.

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

Add '81' to each side of the equation.
-81 + 81 + n2 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + n2 = 0 + 81
n2 = 0 + 81

Combine like terms: 0 + 81 = 81
n2 = 81

Simplifying
n2 = 81

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