Answer:
Step-by-step explanation:
Each x has only 1 y associated with it. It does not have 2 different ys for the same x.
Each entry for x (the domain) in this case, has only 1 y associated with it - the range.
The formal definition of a function is very much the same as the wording I've used for the definitions above.
Mathematically a function is
a process that associates each element of a set X, to a single element of a set Y
