I must calculate
.
My attempt :
Let
. I've calculated the poles of
to be
,
,
and
.
I chose the curve
as being the circle centered at
with radius
.
So I have that
.
It remains to calculate the residues of
, which I wasn't able to do.
I tried to express
as a Laurent series but I didn't succeed in it.
I also tried to use the fact that the residues are worth
but without success in evaluating the limit.
So how could I find the residues of
?
Thanks in advance... and sorry! I find all this very difficult to grasp in such a few time.