All the values of $(8 i)^{\frac{1}{3}}$ are
All the values of $(8 i)^{\frac{1}{3}}$ are
- $\pm(\sqrt{3}+i),-2 i$
- $\pm \sqrt{3}+i,-2 i$
- $\pm \sqrt{3}-i,-2 i$
- $\pm(2+i), i$
Solution
$\begin{aligned}
& (8 i)^{1 / 3}=\left(-8 i^3\right)^{1 / 3}=-2 i \\
& i=e^{i \frac{\pi}{2}}=e^{i \frac{5 \pi}{2}}
\end{aligned}$
$(8 i)^{1 / 3}=2 e^{\frac{i \pi}{6}}=2\left(\frac{\sqrt{3}}{2}+\frac{i}{2}\right)=\sqrt{3}+i$
$(8 i)^{1 / 3}=2 e^{i \frac{5 \pi}{6}}=2\left(\frac{-\sqrt{3}}{2}+\frac{i}{2}\right)=-\sqrt{3}+i$
$(8 i)^{1 / 3}= \pm \sqrt{3}+i,-2 i$.
Asked in: AP EAMCET 2024 (22 May Shift 1)
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