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# The order of $-i$ in the multiplicative group of $4^{th}$ roots of unity is

$\begin{array}{1 1}(1)4&(2)3\\(3)2&(4)1\end{array}$

Can you answer this question?

The roots of fourth roots of unity are
$1.-1,i,-i$
$(-i)^4=i^4=1$
Order of $(-i) =4$
Hence 1 is the correct answer.
answered May 22, 2014 by