Answer:
Yes.
The relation is a function because every element in the domain (the x's) is mapped to one element in the range (the y's).
Explanation:
For a relation that is a set of points all you have to look for while igorning any duplicate points is that all of the x's are different. If there are any 2 (or more) x's that are the same, then it is not a function.
So there are no duplicate points.
For example the set {(1,5),(2,5)(1,5)} is really just {(1,5),(2,5)}.
Anyways the x's in the points are (in order from left to right):
1
-4
3
0
2
All of these are different, I did not list a value for x that was same anywhere in that list. So it is a function.
The relation is a function because there is no x that gets mapped to more than one y.