Answer:
It's not a function.
Explanation:
A function is defined using 3 sets (A, B, and F) where A is the domain, B is the range, and F is the cartesian multiplication between A and B (A x B).
A relation is a function if for every object in the domain, A (in our case, -1 and -4), matches a singular value in the range, B (in our case, 2, 9 and 13).
In this relation, -4 matches with both 9 and 13, therefore, the relation is not a function.