Hi

I was wondering whether someone would be able to have a look at this question and my answer to see if I am correct. If I am not, or the solution requires more information, I would greatly appreciate it if you could show me how solve this problem.

QUESTION:

Find Res(g,0) for g(z) = z^-2 . cosh(z) (I mean z squared multiplied by cosh(z))

MY SOLUTION

= cosh(z) / z^2

cosh(z) = 1 + z^2/2! + z^4/4! + z^6/6!

cosh(z)/z^2 = 1/z^2 + 1/2! + z^2/4! + z^4/6! + .....

This has a pole of order 2 at z = 0

Res(g,0) = 1/2

Thank you

Doug