## Thinking Mathematically (6th Edition)

$y$ is not a function of $x$.
RECALL: If all vertical lines pass through the graph one time at the most, then the graph represents $y$ as a function of $x$. Notice that a number of vertical lines (such as $x=0$) will pass through the graph at more than one point. Thus, the given graph does not represent $y$ as a function of $x$.