## Precalculus (6th Edition)

The relation defines a function. domain: $(-\infty, +\infty)$ range: $(-\infty, +\infty)$
Note that all vertical lines will pass through the graph in at most one point. This means that the graph pass the vertical line test. Thus, the given graph represents a function. The graph covers all real numbers from left to right so the function is defined for all values of $x$. This means the domain is $(-\infty, +\infty)$. The graph covers all real numbers from top to bottom so the function the value of the function (or $y$) can be any real number. This means the range is $(-\infty, +\infty)$.