Alternating Series: -1/3 + 2/4 - 3/5 + 4/6 - 5/7 + ...

summergrl

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Feb 21, 2007
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Test the series for convergence or divergence. I think we are supposed to be using the alternating series test.

-1/3 + 2/4 - 3/5 + 4/6 - 5/7 + ...
 
Check the two conditions of the alternating series.

Your series: \(\displaystyle \L\\\displaystyle\sum_{n=1}^{\infty}(-1)^{n}\frac{n}{n+2}\)

Is it true that: \(\displaystyle \L\\a_{1} \;\ > \;\ a_{2} \;\ > \;\ a_{3} \;\ > \;\ .... \;\ > \;\ a_{k} \;\ > \;\ ....\)

Check the limit:

\(\displaystyle \L\\\lim_{k\to\infty}\frac{n}{n+2}\). Does it equal 0?.
 
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