Hi guys, so i was doing this one question and cant find a way through. It goes by like this :

What is the condition such that the series

1+[7/(3x+5)]+[7+(3x+5)^2].... is converge

hence show that the sum of the above series is 3x-5/3x-12

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- Jul 28th 2012, 01:10 PMnisbahmumtazSeries problem (again!)
Hi guys, so i was doing this one question and cant find a way through. It goes by like this :

What is the condition such that the series

1+[7/(3x+5)]+[7+(3x+5)^2].... is converge

hence show that the sum of the above series is 3x-5/3x-12 - Jul 28th 2012, 01:51 PMemakarovRe: Series problem (again!)
- Jul 28th 2012, 01:57 PMnisbahmumtazRe: Series problem (again!)
My bad. Sorry. It's (3x-5)/(3x-12)

- Jul 28th 2012, 02:05 PMPlatoRe: Series problem (again!)
- Jul 28th 2012, 02:16 PMemakarovRe: Series problem (again!)
And $\displaystyle 1+\sum_{i=1}^\infty\frac{7}{(3x+5)^i}=\frac{3x+11} {3x+4}$ (using geometric progression).

Edit: added ^i to the formula. - Jul 28th 2012, 02:19 PMnisbahmumtazRe: Series problem (again!)
- Jul 28th 2012, 02:25 PMPlatoRe: Series problem (again!)