## Functions Modeling Change: A Preparation for Calculus, 5th Edition

(a) $f(0)=3$ (b) $x = -1,3$ (c) $x \in (-1,3)$
(a) At $x=0$, the vertical value is $3$. So, $f(0)=3$. (b) When the line crosses the x-axis, $f(x)=0$. This happens at $x=-1$ and $x=3$. Therefore, $f(x)=0$ at $x=-1,3$. (c) When the line is above the x-axis, $f(x)>0$. This happens at all values in between $-1$ and $3$, or $x \in (-1,3)$.