Solve by Factoring x^2-121=0

$x^{2} - 121 = 0$

Step 1

Rewrite $121$ as $11^{2}$ .

$x^{2} - 11^{2} = 0$

Step 2

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = x$ and $b = 11$ .

$(x + 11) (x - 11) = 0$

Step 3

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

$x + 11 = 0$

$x - 11 = 0$

Step 4

Set $x + 11$ equal to $0$ and solve for $x$ .

Set $x + 11$ equal to $0$ .

$x + 11 = 0$

Subtract $11$ from both sides of the equation.

$x = - 11$

Step 5

Set $x - 11$ equal to $0$ and solve for $x$ .

Set $x - 11$ equal to $0$ .

$x - 11 = 0$

Add $11$ to both sides of the equation.

$x = 11$

Step 6

The final solution is all the values that make $(x + 11) (x - 11) = 0$ true.

$x = - 11, 11$