## Calculus with Applications (10th Edition)

y is $\textbf{not a function}$ of x.
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).