Alternating Series

Chris*

New member
Joined
Jan 9, 2007
Messages
22
I'm stuck on what I should do for this problem:
Show that the series
\(\displaystyle 1-\frac{2}{5^2}+\frac{3}{5^3}-\frac{4}{5^4}+\cdot \cdot \cdot\) is convergent.

I'm fairly sure that this is an alternating series because the 2nd part of the problems asks to find an estimate with an error less than \(\displaystyle \frac{1}{10,000}\). So, I tried to come up with a formula for the sequence b[sub:1r0jc46r]n[/sub:1r0jc46r] to show it fulfills the conditions of an alternating series, but I couldn't seem to find a formula that could include that first term.

Am I going about this the wrong way? This seems like it should be a straight-forward problem... :?
Any help would be appreciated!
 
Chris* said:
I'm stuck on what I should do for this problem:
Show that the series
\(\displaystyle 1-\frac{2}{5^2}+\frac{3}{5^3}-\frac{4}{5^4}+\cdot \cdot \cdot\) is convergent.

I'm fairly sure that this is an alternating series because ....

It is an alternating series because of consecutive terms alternate in signs (from positive to negative)

[removed - look at Glenn's response below]

the 2nd part of the problems asks to find an estimate with an error less than \(\displaystyle \frac{1}{10,000}\). So, I tried to come up with a formula for the sequence b[sub:x0ap93mp]n[/sub:x0ap93mp] to show it fulfills the conditions of an alternating series, but I couldn't seem to find a formula that could include that first term.

Am I going about this the wrong way? This seems like it should be a straight-forward problem... :?
Any help would be appreciated!
 
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