I must find the Laurent series of at the point and find the radius of convergence of the series.

My attempt: I guess they mean when they say ?

First I realize that has a singularity at and so the radius of convergence of the Laurent series centered at should be equal to .

I'm not sure if I should make a change of variable in order to get the Laurent series centered at or if I should make any other algebra.

What I've done so far is to write as for . But I'm still far from a series of the form .

Any tip would be good for me.