Answer
$\boxed{\textbf{Not a function.}}$
Work Step by Step
A function is a rule that assigns to each element from one set exactly one element from another set.
We can find an x to which more than one y will be assigned:
If $x=8$, then y can be 2 or -2, for the relation to be valid.
( $ 8=2^{2}+4\quad$and$\quad 8=(-2)^{2}+4$)
so
this is not a function.
