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The residue of  at z = 3 is

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Concept:

Residue Theorem:

If f(z) is analytic in a closed curve C except at a finite number of singular points within C, then

Formula to find residue:

1. If f(z) has a simple pole at z = a, then

2. If f(z) has a pole of order n at z = a, then

Calculation:

z = 3 is a simple pole of f(z)

The residue at z = 3 is,

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