Complex Integrals - Poles of Integration Outside the Curve

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SUMMARY

The integral \(\int_{|z-2i|=2} \frac{dz}{z^2-9}\) evaluates to zero because the singularities at \(z=3\) and \(z=-3\) lie outside the contour defined by \(|z-2i|=2\). Since the integrand \(\frac{1}{z^2-9}\) is analytic within the region enclosed by the contour, the Cauchy Integral Theorem confirms that the integral over a closed contour of an analytic function is zero. Thus, the conclusion is definitive: the integral evaluates to zero.

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Homework Statement



[itex]\int_{|z-2i|=2}[/itex] = [itex]\frac{dz}{z^2-9}[/itex]



2. The attempt at a solution

I know that the contour described by |z-2i|=2 is a circle with a center of (0,2) (on the complex plane) with a radius of 2. The singularities of the integral fall outside of the contour (z+3 and z-3). In this case, is the solution just going to be zero or undefined?
 
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Your integrand is analytic in a region that contains your contour, what do you know about a closed contour integral of an analytic function?
 
The integral is 0. Makes sense. Thanks.
 

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