Answer
$x=\pm 2$ or $x=\pm 1$
Work Step by Step
We solve by factoring:
$x^{4}-5x^{2}+4=0$
$(x^{2}-4)(x^{2}-1)=0$
$x^{2}-4=0$ or $x^{2}-1=0$
$x=\pm \sqrt{4}$ or $x=\pm \sqrt{1}$
$x=\pm 2$ or $x=\pm 1$
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.