Here's the problem:

so I use ratio test (obviously):

after some cancellations I have:

It seems that I could say that cancels, but then again, n + 1 will increase faster than n.

I can't figure out where to go from here though. Help? Thanks!

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- Jun 17th 2013, 05:59 PMjjtjpPower Series
Here's the problem:

so I use ratio test (obviously):

after some cancellations I have:

It seems that I could say that cancels, but then again, n + 1 will increase faster than n.

I can't figure out where to go from here though. Help? Thanks! - Jun 17th 2013, 06:33 PMSorobanRe: Power Series
Hello, jjtjp!

Quote:

Here's the problem:

So I use ratio test (obviously):

. We are taking absolute values; drop the (-1)^n.

After some cancellations I have:

It seems that I could say that cancels,

but then again, n + 1 will increase faster than n. . This is not true.

I can't figure out where to go from here though. .Thanks!

We have: .

Divide numerator and denominator by

. .

Therefore: .

- Jun 17th 2013, 06:44 PMjjtjpRe: Power Series
Thanks so much! I wish I had paid more attention in high school, seems like the trivial stuff always trips me up.