Hey MSUMathStdnt.

Given the convergence criteria the sum should be 3 - (1/[1+1/3]) = 3 - 3/4 = 12/4 - 3/4 = 9/4

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- Dec 15th 2012, 09:42 PM #1

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## Sum 3-1+1/3-1/9+...=9/4

I have numerically verified that the following sum comes to , the same thing the back of the book says. So what'd I do wrong?

Find the sum of the convergent series

.

I verified that the above sum can be represented as

,

which can be rewritten as

.

I believe I can apply the geometric series to the summation, giving me

.

Ahhh... but now I see that the geometric series equation starts the summation at (do you find that typing up your answers sometimes helps you realize what's wrong? Why is that?).

So, I need to subtract from my answer, which (unsurprisingly) gives .

- Dec 15th 2012, 11:56 PM #2

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- Dec 16th 2012, 05:08 AM #3

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