# Chapter 1 - Functions - 1.1 Review of Functions - 1.1 Exercises - Page 10: 21

$d$=dependent variable $t$=independent variable Domain: [0,8]

#### Work Step by Step

Since the distance depends on the time that the stone spends in the air, $d$ is the dependent variable and $t$ is the independent variable. The domain consists of the appropriate values of $t$. The stone's path begins at $t=0$ and ends when it hits the ground. We find the time that it hits the ground by setting $d=0$: $40t-5t^2=5t(8-t)0$ $t=0$, $t=8$ Thus the domain is: [0,8]

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