Another Laurent Expansion Question

[brianhawaiian]

Homework Statement

Find all possible Laurent expansions centered at 0 for
(z - 1) / (z + 1)

Find the Laurent Expansion centerd at z = -1 that converages at z = 1/2 and determine the largest opens et on which
(z - 1) / (z + 1) converges

Homework Equations

The Attempt at a Solution

(z - 1) / (z + 1) breaks down into [z / (z+1)] - [1 / (z+1)]

For the first one divide out the z to obtain 1 / 1 + (1/z) I think? However not being in the form 1 / 1 - (1/z) would this be the same series but negative? That doens't seem right.

For breaking down -1 / (z + 1) I didn't know how to attack that one.

 

[brianhawaiian]

Anything?