Use Cauchy Residue Theorem to find the integral

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SUMMARY

The integral ∫^{2∏}_{0}\frac{cosθ}{13+12cosθ} can be evaluated using the Cauchy Residue Theorem, yielding a result of -\frac{4∏}{15}. The discussion highlights a common error in the factorization of the polynomial 6z^3+13z^2+6z, which should be correctly expressed as 6z(z+2/3)(z+3/2). The application of the substitution method is also emphasized as crucial for solving the integral accurately.

PREREQUISITES
  • Cauchy Residue Theorem
  • Complex analysis fundamentals
  • Polynomial factorization techniques
  • Trigonometric integrals
NEXT STEPS
  • Study the application of the Cauchy Residue Theorem in complex integrals
  • Learn polynomial factorization methods for cubic equations
  • Explore substitution methods in trigonometric integrals
  • Review examples of integrals evaluated using residues
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Students of complex analysis, mathematicians working on integral calculus, and anyone seeking to master the application of the Cauchy Residue Theorem in evaluating integrals.

DanniHuang
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Homework Statement



To find the integral by Cauchy Residue Theorem and apply substitution method.

Homework Equations



To show: ∫[itex]^{2∏}_{0}[/itex][itex]\frac{cosθ}{13+12cosθ}[/itex]=-[itex]\frac{4∏}{15}[/itex]

The Attempt at a Solution


The solution I have done is attached. It is different as what the question wants me to show. I do not know where I did it wrong.
 

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Otherwise it looks fine to me, except that
[tex]6z^3+13z^2+6z = 6 z(z+2/3)(z+3/2) \neq z(z+2/3)(z+3/2)[/tex]
 

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