## Precalculus (6th Edition) Blitzer

$y$ is not a function of $x$
RECALL: If all vertical lines will pass through the graph in at most one point, then the graph represents $y$ as a function of $x$. Otherwise, the graph does not represent $y$ as a function of $x$. Notice that a number of vertical lines (such as x = -3) will pass through the graph at two different points. The graph fails the vertical line test. Thus, the given graph does not represent $y$ as a function of $x$.