Answer
y is $\textbf{not a function}$ of x.
Work Step by Step
A function is a rule that assigns to each element from one set exactly one element from another set.
For any x$\neq$0, say x=1
y can be +1 or -1 for the relation to be valid,
so this rule is not a function
(one x-value can have more than one y-value assigned).
