Determine whether a relation is function.
We know a relation is a function only if it relates each element in its domain (input) to only one element in the range (output).
So from the above diagram, we can see a well-defined one-to-many mapping from the domain onto the range .
So, the ordered pairs are
Here, the input has two outputs and . So, the relation is not a function.
Hence, the relation is not a function.