Hi,

T is a function,

where, X are i.i.d Bernoulli r.v

The end point of the derivation is,

I am given,

, so

From a previous step, I know that Prob(X = 1) = 0.5, and Prob(X = -1) = 0.5

So the Expected values are

for X = 1, and for X=-1

So the =

At this point it looks like the answer should be

I can't see where the nth power around the brackets should come from.

ie.

Any ideas?