Answer
Not a real number
Work Step by Step
$\sqrt[n] a$ can be written as $a^{1/n}$.
$\sqrt[4] {-256}=(-256)^{1/4}$
$\sqrt[4] {-256}$ is not a real number.
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.