Final answer:
The given relation {(4,2),(6,6),(9,9)} is a function because each input is paired with only one output and there are no repeated x-values.
Step-by-step explanation:
To determine whether a relation is a function, we need to check if each input (or x-coordinate) maps to exactly one output (or y-coordinate). In the given set {(4,2),(6,6),(9,9)}, we observe that each x-coordinate is paired with only one y-coordinate, and there are no repeated x-values with different y-values. Hence, this relation is indeed a function because it satisfies the definition of a function that for every input there is only one output.