Answer
$\dfrac{\sqrt[4] {y}}{3x}$
Work Step by Step
$\sqrt[4] {\dfrac{y}{81x^{4}}}=\dfrac{\sqrt[4] {y}}{\sqrt[4] {81x^{4}}}=\dfrac{\sqrt[4] {y}}{3x}$
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.