Algebra Examples

$\frac{x - 7}{x + 9}$

Set the denominator in $\frac{x - 7}{x + 9}$ equal to $0$ to find where the expression is undefined.

$x + 9 = 0$

Subtract $9$ from both sides of the equation.

$x = - 9$

The domain is all values of $x$ that make the expression defined.

Interval Notation:

$(- \infty, - 9) \cup (- 9, \infty)$

Set-Builder Notation:

${x | x \neq - 9}$