Contour Integral of |z| = 2 using Cauchy's Formula

muzak
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Homework Statement


|z| = 2, \oint\frac{1}{z^3}


Homework Equations


Cauchy's Integral Formula
http://en.wikipedia.org/wiki/Cauchy's_integral_formula

The Attempt at a Solution


Seems like a simple application of the general formula on the wiki page with n = 2, a = 0, and f(z) = 1. The higher order derivatives just yield zero, making the integral zero. Just asking for verification for a friend.
 
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You're using a circle of radius 2 as a contour. You could parametrize it with some ##z(t)##, and then evaluate it. Think about ##e##, and see what you get.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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