Intermediate Algebra for College Students (7th Edition)

domain: $\left\{1, 2\right\}$ range: $\left\{-6, 4, 6\right\}$ The relation is not a function.
The domain is the set that contains all of the first coordinates. Thus, the domain is $\left\{1, 2\right\}$. The range is the set that contains all of the second coordinates. Thus, the range is $\left\{-6, 4, 6\right\}$. The requirement for a function is that each input (part of the domain) has exactly one output (part of the range). The first coordinate $2$ is paired with two different second coordinates, (6 and -6). Therefore the given relation is not a function.