(c+9)(c-9)=

Solution for (c+9)(c-9)= equation:

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

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

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

Multiply (9 + c) * (-9 + c)
(9(-9 + c) + c(-9 + c)) = 0
((-9 * 9 + c * 9) + c(-9 + c)) = 0
((-81 + 9c) + c(-9 + c)) = 0
(-81 + 9c + (-9 * c + c * c)) = 0
(-81 + 9c + (-9c + c2)) = 0

Combine like terms: 9c + -9c = 0
(-81 + 0 + c2) = 0
(-81 + c2) = 0

Solving
-81 + c2 = 0

Solving for variable 'c'.

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

Add '81' to each side of the equation.
-81 + 81 + c2 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + c2 = 0 + 81
c2 = 0 + 81

Combine like terms: 0 + 81 = 81
c2 = 81

Simplifying
c2 = 81

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