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At $z = 0$ the function $f(z)=(e^z+1)/(e^z-1)$ has
1. A removable singularity
2. A pole
3. An essential singularity
4. The residue of $f (z )$ at $z = 0$ is $2$.

i am completely stuck on it.please help somebody.thanks.

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    do you know the definition of the concepts you mention in the options?2012-12-21

4 Answers 4