Need help calculating convergence, series.
I have an exercise where I'm supposed to find convergence if any and if there are show how it's... constituted. The series:
I'd like help when it comes to ways of solving it. I solve it as a real problem, getting the zeros on the real axis. Then I use these to find the zeros in the img-plane.
For what z is the fraction smaller than 1?
I get - treating z as a real variable, so centre on x-axis should be
Now to the imaginary part.
I get - which goes nicely with the real values.
First on all, is this right? And is there a more solid way of doing this?