Precalculus Examples

$a (r) = r + \frac{1}{r - 1}$

Step 1

Set the denominator in $\frac{1}{r - 1}$ equal to $0$ to find where the expression is undefined.

$r - 1 = 0$

Step 2

Add $1$ to both sides of the equation.

$r = 1$

Step 3

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

Interval Notation:

$(- \infty, 1) \cup (1, \infty)$

Set-Builder Notation:

${r | r \neq 1}$

Step 4