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Complex numbers and induction

  1. Sep 20, 2008 #1
    1. The problem statement, all variables and given/known dataIf z is a non-real complex number such that z+1/z=2costheta, prove that z^n+1/z^n=2cosntheta for any posistive integer n

    2. Relevant equations
    I think the process of induction would work, but im not quite sure how to do that with all of the unknowns, would i just treat costheta as a constant number

    3. The attempt at a solution
  2. jcsd
  3. Sep 20, 2008 #2


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    ...does that help?
  4. Sep 20, 2008 #3


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    If z=cosx+isinx, what is z^n?
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