# What is the domain of f(x) = 5/(x-9)?

Sep 21, 2015

$\left\{x | x \ne 9\right\}$

#### Explanation:

The domain is the set of values of $x$ for which the function is defined. The function $f \left(x\right) = \frac{5}{x - 9}$, will only be undefined if the denominator is 0. Simply look for the value of $x$ that will make the denominator 0.

$x - 9 = 0$
$x = 9$

The domain is the set of all real numbers except for 9.
$\left\{x | x \ne 9\right\}$