$$\left. \begin{array} { l } { x ^ { 4 } + 1 = 0 } \end{array} \right.$$
$x=\sqrt{2}\left(-\frac{1}{2}+\frac{1}{2}i\right)\approx -0.707106781+0.707106781i$
$x=\sqrt{2}\left(\frac{1}{2}-\frac{1}{2}i\right)\approx 0.707106781-0.707106781i$
$x=\sqrt{2}\left(\frac{1}{2}+\frac{1}{2}i\right)\approx 0.707106781+0.707106781i$
$x=\sqrt{2}\left(-\frac{1}{2}-\frac{1}{2}i\right)\approx -0.707106781-0.707106781i$
