Given that the sum to infinity of a G.P. is denoted by S.

Show that if a > 0, then S > 4ar except for one value of r.

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- Feb 17th 2013, 06:31 AMmoonchildvulcanGeometric Series Question
Given that the sum to infinity of a G.P. is denoted by S.

Show that if a > 0, then S > 4ar except for one value of r. - Feb 17th 2013, 06:55 AMSorobanRe: Geometric Series Question
Hello, moonchildvulcan!

Quote:

The sum of an infinite G.P. is:.

If isto , we have: .*equal*

. .

. .

- Feb 17th 2013, 06:56 AMa tutorRe: Geometric Series Question
If you start with you can arrive at your conclusion.

- Feb 17th 2013, 07:14 AMmoonchildvulcanRe: Geometric Series Question
Thanks for that. I still cannot see why S > 4ar in the first place. The rest that follows, I managed to achieve.

- Feb 17th 2013, 07:31 AMmoonchildvulcanRe: Geometric Series Question
- Feb 17th 2013, 08:46 AMa tutorRe: Geometric Series Question
I started by assuming the conclusion to see where it lead.

but this works in reverse too so starting with if you get the result you want.