Integrate $\oint \frac{e^z}{z^2-1}dz$ over $\gamma$ being the circle centered at $0$ of radius $2$.

complex-analysiscontour-integration

So I need to integrate

$$\oint_\gamma \frac{e^z}{z^2-1}dz$$

where $\gamma$ is the circle of radius $2$ centered at $0$. So by the residue theorem I have that

$$\oint_\gamma \frac{e^z}{z^2-1}dz = 2 \pi i \bigg( \text{Res}(\frac{e^z}{z^2-1};1)+ \text{Res} (\frac{e^z}{z^2-1};-1) \bigg)= \pi i (e-e^{-1})$$

So I calculated the residues at the two points of singularity. Namely, $z=\pm 1$. Did I do it correctly?

Best Answer

Your final answer is right, but you should write $$\text{Res}\left(\frac{e^z}{z^2-1}, \pm 1\right)$$ instead of those functions. The functions you put inside does not even have singularity there.

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