# Math Help - (Laurent) Series Expansion

1. ## (Laurent) Series Expansion

Show that the series expansion for arctan(z) = z -z^3/3 + z^5/5 - z^7/7 + .... .

2. start by using $\arctan z=\int_{0}^{z}{\frac{dt}{1+t^{2}}}=\int_{0}^{z}{\l eft( \sum\limits_{j=0}^{\infty }{\left( -t^{2} \right)^{j}} \right)\,dt}.$