I don't know why the correct answer is that one.
I would say that since the principal part is composed of infinitely many terms, it's an essential singularity
It's not an "essential singularity" at x= 0 because the function is NOT DEFINED in any neighborhood of 0! The definition clearly says the series is "convergent for z> 3".
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
