I want to use the theorem any holomorphic function on Rieman sphere is a rational function, and hence a polynomial. So, I want to show that $f$ is holomorphic on Rieman sphere. So first thing I am trying to do is show that $\infty$ is a removable singularity, since if it is removeable $f$ can extend to a holomorphic function on Rieman sphere then I can apply the theorem I mentioned and I am done. But I am having trouble showing that.
Any hint and nudge toward right direction would be great!
Thanks!