Answer
The input $\frac{1}{2}$ has three outputs; $-2,0$ and $4$. In the case of a function, each input should have exactly one output. So, the given relation is not a function.
Work Step by Step
Work is not needed.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.