Factor
$x^{2}-81$
The factored form of $x^{2}-81$ is \(\boxed{(x - 9)(x + 9)}\)
Step 1 :Factor the expression $x^{2}-81$
Step 2 :Recognize this as a difference of squares problem. The difference of squares formula is $a^{2} - b^{2} = (a - b)(a + b)$
Step 3 :In this case, $a = x$ and $b = 9$ because $9^{2} = 81$
Step 4 :Rewrite $x^{2} - 81$ as $(x - 9)(x + 9)$
Step 5 :The factored form of $x^{2}-81$ is \(\boxed{(x - 9)(x + 9)}\)