Equating powers of conjugate complex numbers

Equating powers of conjugate complex numbers

IB Year 6 | Grade 12

Consider two complex numbers \(z=(1+i)^p\) and \(w=(1-i)^q\) where \(p\) and \(q\) are positive integers.

  1. Express each of \(z\) and \(w\) in polar form, giving your answers in terms of \(p\) and \(q\).
  2. Find the smallest values of \(p\) and \(q\) such that \(z=w\).

Solution:

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Answer:(a) \(z=2^{p/2}(\cos\alpha_p+i\sin\alpha_p),\ \alpha_p\equiv\frac{p\pi}{4}\pmod{2\pi};\quad w=2^{q/2}(\cos\beta_q+i\sin\beta_q),\ \beta_q\equiv-\frac{q\pi}{4}\pmod{2\pi},\ \alpha_p,\beta_q\in(-\pi,\pi]\) (b) \(p=q=4\)

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