Answer
$y$-axis
Work Step by Step
When an equation's graph is symmetric with respect to the $y$-axis, inputting both $x$ and $-x$ into the equation will produce the same value of $y$.
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.