# Thread: question - derive a laurent series

1. ## question - derive a laurent series

hi

$f(z) = 2z / (z + j)$

derive a laurent series for the function about the centre -j.

i'm really stuck on this question..

can anyone help...?

2. Originally Posted by kevinfromuoa
hi

$f(z) = 2z / (z + j)$

derive a laurent series for the function about the centre -j.

i'm really stuck on this question..

can anyone help...?
All you have do in this case is a polynomial division:

$\frac{2z}{z + j} = 2 - \frac{2j}{z + j} = 2 - \frac{2j}{z - (-j)}$.

Done.