A set of ordered pairs is said to be a relation. So the given pairs form a relation. For a relation to be a function, the condition that must be satisfied is that the first element of its ordered pairs should not be paired with more than 1 value.
In simple words it can be said that the x-values should only occur once for a relation to be a function. In the given ordered pairs, -1 is occurring twice, hence this relation is not a function.
Hence the set of ordered pairs is only a relation.
