Answer
$x=\pm 4$ or $x=\pm 4i$
Work Step by Step
We solve by factoring:
$x^{4}-256=0$
$(x^{2}-16)(x^{2}+16)=0$
$x^2-16=0$ or $x^2+16=0$
$x=\pm\sqrt{16}$ or $x=\pm\sqrt{-16}$
$x=\pm 4$ or $x=\pm 4i$
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