How to Prove z^n + 1/z^n = 2cos(nθ) Using Induction?

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SUMMARY

The discussion focuses on proving the equation z^n + 1/z^n = 2cos(nθ) using mathematical induction, given that z is a non-real complex number satisfying z + 1/z = 2cos(θ). Participants suggest that treating cos(θ) as a constant simplifies the induction process. The representation of z as e^(iθ) is introduced, which aids in deriving z^n as (cos(θ) + i sin(θ))^n, leveraging Euler's formula for complex numbers.

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  • Understanding of complex numbers and Euler's formula
  • Familiarity with mathematical induction techniques
  • Knowledge of trigonometric identities
  • Basic algebra involving complex exponentials
NEXT STEPS
  • Study the principles of mathematical induction in depth
  • Explore Euler's formula and its applications in complex analysis
  • Review trigonometric identities related to cosines and their properties
  • Practice problems involving complex exponentials and their powers
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Students studying complex analysis, mathematics educators, and anyone interested in advanced algebraic proofs involving induction and trigonometric functions.

mikee
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Homework Statement

If 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



Homework Equations


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


The Attempt at a Solution

 
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mikee said:

Homework Statement

If 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



Homework Equations


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


The Attempt at a Solution


Apparently
[tex] z=e^{i\theta}[/tex]
...does that help?
 
If z=cosx+isinx, what is z^n?
 

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