Hi all,

I'm trying to find:

I manipulate this the following way:

Is this right? Thanks

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- February 2nd 2013, 12:36 PMdirectorSum of this geometric series
Hi all,

I'm trying to find:

I manipulate this the following way:

Is this right? Thanks - February 2nd 2013, 01:58 PMShakarriRe: Sum of this geometric series
Yes you can derive that result directly in the same way that the general formula is derived, I just tried it myself and the peculiar common ratio in the series does not change the derivation.

- February 2nd 2013, 02:10 PMdirectorRe: Sum of this geometric series
I see, thanks. Now, If I want to obtain the sum from just the real part of ,

that is,

Could I start from:

and then continue this way:

Or is there an easier method? - February 5th 2013, 02:49 AMibduttRe: Sum of this geometric series
The expression for sum of n terms of a GP is

Attachment 26861 Now I am sure you can make out where did you go wrong - February 5th 2013, 02:53 AMProve ItRe: Sum of this geometric series
Actually it's ...