\(n\)th roots of a complex number

\(n\)th roots of a complex number

IB Year 6 | Grade 12
  1. Express the complex number \(1 + i\) in the form \(\sqrt{a}\mathrm{e}^{i\frac{\pi}{b}}\), where \(a, b \in \mathbb{Z}^+\).
  2. Using the result from (a), show that \(\left(\frac{1 + i}{\sqrt{2}}\right)^n\), where \(n \in \mathbb{Z}\) has only eight distinct values.
  3. Hence solve the equation \(z^8 - 1 = 0\).

Solution:

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Answer:(a) \(a=2,\ b=4\). (b) Exactly eight values. (c) \(z=\mathrm e^{ik\pi/4}\), \(k=0,1,\ldots,7\).

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