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Math Help - Infinite Geometric Series

  1. #1
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    Infinite Geometric Series

    Hey guys, I am having difficulty with this problem so please help, and here it is.

    edit: I don't know how to type this problem in it's original format so please bear with it.

    E (sigma sign), with an infinite sign above it and with 'i'=0 below it. Then to its right is the equation 3i + 5/4i.

    How would I find the initial value a1 and the 'r' value? This is a sum of the infinite geometric series problem.

    Any help of feedback would be greatly appreciated, thanks.
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  2. #2
    Behold, the power of SARDINES!
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    Quote Originally Posted by Gitano View Post
    Hey guys, I am having difficulty with this problem so please help, and here it is.

    edit: I don't know how to type this problem in it's original format so please bear with it.

    E (sigma sign), with an infinite sign above it and with 'i'=0 below it. Then to its right is the equation 3i + 5/4i.

    How would I find the initial value a1 and the 'r' value? This is a sum of the infinite geometric series problem.

    Any help of feedback would be greatly appreciated, thanks.
    ummmm...... If this is what you mean it is not a geometric series

    \sum_{i=0}^{\infty}\frac{3i+5}{4i}

    If you meant this it is also not geometric

    \sum_{i=0}^{\infty}3i +\frac{5}{4i}

    either way since i goes to infinity both series diverge
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  3. #3
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    I meant the first equation you posted. Well the question says to find the sum of the series and according to the answer key, it is 32/3. I am just not quite sure as to how to get that answer.

    Thanks for the feedback.
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  4. #4
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    I strongly suspect you have misread the problem. In the first place, it is NOT a "geometric series" as TheEmptySet said. In the second place, it is NOT defined when i= 0 and so the sum is impossible!

    Go back and check the problem carefully.
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  5. #5
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    Quote Originally Posted by HallsofIvy View Post
    I strongly suspect you have misread the problem. In the first place, it is NOT a "geometric series" as TheEmptySet said. In the second place, it is NOT defined when i= 0 and so the sum is impossible!

    Go back and check the problem carefully.

    Yeah maybe you are right. By looking at 'i'=0 I knew the initial value was undefined and that the problem was possibly not a geometric series. It is just the answer key that threw me off. Maybe the answer key is wrong.
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