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Homework Help: Find the sum of the convergent series 4-2+1-1/2

  1. May 18, 2010 #1
    find the sum of the convergent series 4-2+1-1/2 ....

    1. The problem statement, all variables and given/known data

    find the sum of the convergent series . 4-2+1-1/2...

    2. Relevant equations

    sum of r^n |r|< 1 --> 1/(1-r)= sum

    3. The attempt at a solution
    4(1-1/2+1/4-1/8...)
    I can see a pattern here where the denominator is going 2,4,8 so its like 1*2, 2*2, 2*2*2 but the 1 and + and the - throws me off...can someoen help me?
     
  2. jcsd
  3. May 18, 2010 #2
    Re: find the sum of the convergent series 4-2+1-1/2 ....

    If this in fact is a geometric series, what would the common ratio be?
     
  4. May 18, 2010 #3

    Cyosis

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    Homework Helper

    Re: find the sum of the convergent series 4-2+1-1/2 ....

    Hint: incorporate [itex](-1)^n[/itex] to solve your sign problem.
     
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