Precalculus Examples

$s (y) = \frac{7 y}{y + 9}$

Step 1

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

$y + 9 = 0$

Step 2

Subtract $9$ from both sides of the equation.

$y = - 9$

Step 3

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

Interval Notation:

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

Set-Builder Notation:

${y | y \neq - 9}$

Step 4