x(x-21)=0

Solution for x(x-21)=0 equation:

Simplifying
x(x + -21) = 0

Reorder the terms:
x(-21 + x) = 0
(-21 * x + x * x) = 0
(-21x + x2) = 0

Solving
-21x + x2 = 0

Solving for variable 'x'.

Factor out the Greatest Common Factor (GCF), 'x'.
x(-21 + x) = 0

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

Simplifying
x = 0

Solving
x = 0

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

Simplifying
x = 0
Subproblem 2
Set the factor '(-21 + x)' equal to zero and attempt to solve:

Simplifying
-21 + x = 0

Solving
-21 + x = 0

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

Add '21' to each side of the equation.
-21 + 21 + x = 0 + 21

Combine like terms: -21 + 21 = 0
0 + x = 0 + 21
x = 0 + 21

Combine like terms: 0 + 21 = 21
x = 21

Simplifying
x = 21
Solution
x = {0, 21}