# How do you find the domain of f(x) = (x^2 - 1)/( x +4)?

Nov 14, 2017

$x \in \mathbb{R} , x \ne - 4$

#### Explanation:

$\text{the denominator of "f(x)" cannot be zero as this would}$
$\text{make "f(x)" undefined}$

$\text{equating the denominator to zero and solving gives}$
$\text{the value that x cannot be}$

$\text{solve "x+4=0rArrx=-4larrcolor(red)"excluded value}$

$\text{domain is } x \in \mathbb{R} , x \ne - 4$