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Problem 5
Discuss the singularities of $$ f(z)=\frac{z^{3}\left(z^{2}-1\right)(z-2)^{2}}{\sin ^{2}(\pi z)} e^{1 / z^{2}} $$ Classify which of these are poles, removable singularities and essential singularity.
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Determine the order of the pole at \(z=0\) for (i) \(f(z)=\frac{z}{\sin z-z+z^{3} / 3 !}\) (ii) \(f(z)=\frac{z}{\left(\sin z-z+z^{3} / 3 !\right)^{2}}\).
How many roots of the equation \(z^{4}+z^{3}+1=0\) have modulus between \(3 / 4\) and \(3 / 2 ?\)
If \(f(z)\) is analytic and nonzero in the disk \(|z|<1\), prove that for \(0<\) \(r<1\) $$ \exp \left(\frac{1}{2 \pi} \int_{0}^{2 \pi} \log \left|f\left(r e^{i \theta}\right)\right| d \theta\right)=|f(0)| . $$
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