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**Bishmay****Member**- Registered: 2013-02-14
- Posts: 2

Check for analyticity: f(z)= 1/(1-z^4)

Please show the steps... Should I start with z= x+iy or take rcoso +i sino????

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 81,652

Hi;

Aren't rational functions analytic away from their poles?

**In mathematics, you don't understand things. You just get used to them.I have the result, but I do not yet know how to get it.All physicists, and a good many quite respectable mathematicians are contemptuous about proof.**

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**Bishmay****Member**- Registered: 2013-02-14
- Posts: 2

Hi,

The complex function is given and it is asked to check whether it is analytic or not... But I am confused how to proceed

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 81,652

Hi;

Your poles are

1, -1, i, -i

A rational function is analytic at each point of its domain. Does that help a bit? What is the domain of your function?

*Last edited by bobbym (2013-02-14 09:27:34)*

**In mathematics, you don't understand things. You just get used to them.I have the result, but I do not yet know how to get it.All physicists, and a good many quite respectable mathematicians are contemptuous about proof.**

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