Simplifying
k2 = k

Solving
k2 = k

Solving for variable 'k'.

Reorder the terms:
-1k + k2 = k + -1k

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

Factor out the Greatest Common Factor (GCF), 'k'.
k(-1 + k) = 0

Subproblem 1
Set the factor 'k' equal to zero and attempt to solve:

Simplifying
k = 0

Solving
k = 0

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

Simplifying
k = 0
Subproblem 2
Set the factor '(-1 + k)' equal to zero and attempt to solve:

Simplifying
-1 + k = 0

Solving
-1 + k = 0

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

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

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

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

Simplifying
k = 1
Solution
k = {0, 1}