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Need help with a question

  1. Sep 25, 2011 #1
    I want to know how to start this problem, but don't want the answer.
    If someone can just help me get started or give me a tip on how to approach these kinds of questions
     

    Attached Files:

  2. jcsd
  3. Sep 25, 2011 #2
    Well, just try to see what happens when you add the terms up to a certain term an in your sequence, to get Sn:

    S1=1

    S2=1+3=4

    S3=1+3+5=9



    And make a guess, then use induction or some other formula.

    What is your guess for Sn=a1+a2+...+an ?
     
  4. Sep 26, 2011 #3
    1+3+5+...+(2n-5)+(2n-3)+(2n-1) =
    = 1+(2n-1) +3+(2n-3) +5+(2n-5)+...
    Do you see a simplification ?
     
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