## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Domain = $\{t\in \mathbb{R}\ \ |\ 0\leq t\leq 60\}$
If a function is used as a model for an application, the problem situation may require restrictions on the domain. For example, length and time are generally nonnegative, and a person's age does not increase indefinitely. $t$ is a nonnegative value, and so is $r(t),$ so we restrict t with $900-15t\geq 0\qquad$... add 15t $900\geq 15t\qquad$... divide with 15 $60\geq t$ Domain = $\{t\in \mathbb{R}\ \ |\ 0\leq t\leq 60\}$