Solve by Factoring x^2-21x=0

$x^{2} - 21 x = 0$

Step 1

Factor $x$ out of $x^{2} - 21 x$ .

Factor $x$ out of $x^{2}$ .

$x \cdot x - 21 x = 0$

Factor $x$ out of $- 21 x$ .

$x \cdot x + x \cdot - 21 = 0$

Factor $x$ out of $x \cdot x + x \cdot - 21$ .

$x (x - 21) = 0$

Step 2

If any individual factor on the left side of the equation is equal to $0$ , the entire expression will be equal to $0$ .

$x = 0$

$x - 21 = 0$

Step 3

Set $x$ equal to $0$ .

$x = 0$

Step 4

Set $x - 21$ equal to $0$ and solve for $x$ .

Set $x - 21$ equal to $0$ .

$x - 21 = 0$

Add $21$ to both sides of the equation.

$x = 21$

Step 5

The final solution is all the values that make $x (x - 21) = 0$ true.

$x = 0, 21$