Answer:
Relation 1: Not a function
Relation 2: Not a function
Relation 3: Function
Relation 4: Not a function
Explanation:
Recall: a relation can only be a function if and only if each domain value has only 1 range value mapped to it or related to it. This means that a domain value can only have exactly one range value for the relation to be qualified a function.
✔️Relation 1 is NOT A FUNCTION.
Rationale: Two of the domain values (star and sky) is having more than 1 range value assigned to each.
✔️Relation 2 is NOT A FUNCTION:
Rationale: domain value, 9, has several range values assigned to it.
✔️Relation 3 is A FUNCTION:
Rationale: each domain value do not have more than one range values assigned to it.
✔️Relation 4 IS NOT A FUNCTION:
Rationale: the domain value, 6, has two range values, m and d, assigned to it.