what is cauchy gorsat theorem.What says it.İ can't understand it.apply the cauchy goursat theorem f(z)=z*z/z-3. IzI=1
how can I do that?

Here is a good explanation of the theorem... but how to apply your forumula to it I am not sure:
http://www.mathreference.com/cx,cgt.html

And here is a links list for more:
http://www.google.com/search?num=100&hl=en&newwindow=1&safe=off&q=%22cauchy+goursat+theorem%22&spell=1