ok, here's my problem translating: it says- R>0 "show that", and then it gives the sugestion of integrating that last function over a convinient path. i'm having a lot of trouble with this. it's supposed to be about Cauchy's theorem and you should need cauchy's formula (f(zo)=1/2pi.i(integral around zo) hope this isn't such a mess. ill get back to this to provide more details if needed. thanks for any help in advance.