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Determine whether the series is convergent or divergent.

  1. Nov 18, 2010 #1
    Hello,

    I have to determine whether the series converges or diverges.

    It is [tex]\Sigma[/tex] (-1)^n * cos(Pi/n) where n=1 and goes to infinity.

    First I took the absolute value of the function and got the limit from n to infinity of cos(pi/n) and as a result I got 1 because cos(0)=1. However my text book says it's divergent. Could you please help me understand why it is divergent?

    Thank you!
     
  2. jcsd
  3. Nov 18, 2010 #2
    Nevermind! I figured out why. I guess I confused the alternating series test with some other one. :)

    Thanks!
     
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