By definition we have to:
A mathematical function is a relationship that is established between two sets, through which each element of the first set is assigned a single element of the second set or none.
The initial set or starting set is also called the domain; the final set or set of arrival, meanwhile, can be called codomain.
We have the following information:
{(-5.2), (-2.5), (0.7), (0.9)}
The data does not represent a function because two different values of the range belong to an element of the domain:
(0.7)
(0.9)
Answer:
The relation is not a function.