(k+1)(k-1)=0

Solution for (k+1)(k-1)=0 equation:

Simplifying
(k + 1)(k + -1) = 0

Reorder the terms:
(1 + k)(k + -1) = 0

Reorder the terms:
(1 + k)(-1 + k) = 0

Multiply (1 + k) * (-1 + k)
(1(-1 + k) + k(-1 + k)) = 0
((-1 * 1 + k * 1) + k(-1 + k)) = 0
((-1 + 1k) + k(-1 + k)) = 0
(-1 + 1k + (-1 * k + k * k)) = 0
(-1 + 1k + (-1k + k2)) = 0

Combine like terms: 1k + -1k = 0
(-1 + 0 + k2) = 0
(-1 + k2) = 0

Solving
-1 + k2 = 0

Solving for variable 'k'.

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

Add '1' to each side of the equation.
-1 + 1 + k2 = 0 + 1

Combine like terms: -1 + 1 = 0
0 + k2 = 0 + 1
k2 = 0 + 1

Combine like terms: 0 + 1 = 1
k2 = 1

Simplifying
k2 = 1

Take the square root of each side:
k = {-1, 1}