Thread: simple sigma operation question

How does one complete a summing operation where

and

and

a sum like

and for

where i is the index


i expanded it like this:

and in this case n = 4

My question, assuming I expanded correctly, stands thus: since the set of X has only 3 elements so how do I compele this operation?

thanks!

You seem to understand it correctly.









makes no sense, because there is no value given. It's undefined here.