Question regarding Cauchy Integral formula

133 Views Asked by At

I have a question regarding Cauchy Integral formula, I was given an assignment questions, and my professor uploaded a solution and i do not understand how he reached to an answer with his method. Can anyone provide me with a clearer method? [Part 2]enter image description here

Solution

1

There are 1 best solutions below

0
On BEST ANSWER

HINT:

The solutions to $z^{10}+2=0$ are found as

$$z^{10}=-2\implies z^{10}=2e^{i(2n+1)\pi}\implies z=2^{1/10}e^{i(2n+1)\pi/10}\implies |z|=2^{1/10}<2$$

Thus, all roots of $z^{10}+2=0$ lie within the region $|z|<2$. Therefore, the poles of $\frac{z^{10}}{(z-1/2)(z^{10}+2)}$ are at $z=1/2$ and $z=2^{1/10}e^{\pm i(2n+1)\pi/10}$ for $n=0,1,2,3,4$.