Consider the relation given by the set of ordered pairs: $\{(9, -3), (4, -2), (1, -1), (0, 0), (1, 1), (4, 2), (9, 3)\}$. To determine if this relation is a mathematical function, we inspect the coordinates. The $x$-value $9$ is matched with two different $y$-values ($-3$ and $3$), and the $x$-value $4$ is matched with two different $y$-values ($-2$ and $2$). Because an $x$-value corresponds to more than one $y$-value, this relation is not a function. The domain is $\{0, 1, 4, 9\}$ and the range is $\{-3, -2, -1, 0, 1, 2, 3\}$.