# General Exapansion

1. Apr 7, 2009

### boneill3

Hi Guys,
I have been asked to do expand E[(1-tX)^-1] for the first 3 terms
Is there are good formula to use to do this?

with the value E, I take it is is the Expected Value. does that get included in the expansion?
regards
Brendan

2. Apr 8, 2009

### Focus

You need to use the fact that
$$\mathbb{E}[f(X)]=\int_{\mathbb{R}}f(x) \mathbb{P}(X \in dx)$$
and the binomial expansion using the linearity of the integral.