## Precalculus (6th Edition)

The given relation represents $y$ as a function of $x$. domain: $(-\infty, +\infty)$ range: $[0, +\infty)$
RECALL: Vertical Line Test If all vertical lines will pass through the graph of a relation in at most one point only, then the relation defines $y$ as a function of $x$. To know if the given graph represents $y$ as a function of $x$, perform the vertical line test. Note that all vertical lines will pass through the given graph at exactly one point only. This means that the graph pass the vertical line test. Thus, the given relation represents $y$ as a function of $x$. The graph covers all x-values so the domain is $(-\infty, +\infty)$. The graph covers y-values that are greater than or equal to $0$ so the range is $[0, +\infty)$.