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Math Help - Limit Comparison Test

  1. #1
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    Limit Comparison Test

    This seems like a fairly easy problem, but i'm not getting the book's answer.

    The sum from x=1 to infinity of 2x^2-1/3x^5+2x+1

    The book seems to expunge enough to make a reference series 1/x^3, which is a p-series. I just don't see how you can expunge that much..

    The question is as written in the book and asks: Use the Limit Comp. Test to determine the convergence or divergence of the series. No parenthesis are needed. the ^ implies something raised to a power.
    Last edited by bakeit1; May 4th 2008 at 11:45 AM.
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  2. #2
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    Quote Originally Posted by bakeit1 View Post
    This seems like a fairly easy problem, but i'm not getting the book's answer.

    The sum from x=1 to infinity of 2x^2-1/3x^5+2x+1

    The book seems to expunge enough to make a reference series 1/x^3, which is a p-series. I just don't see how you can expunge that much..
    Can you group some things with parenthesis to make it a little more clear as to what the question is.
    Thank you!
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  3. #3
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    Quote Originally Posted by bakeit1 View Post
    This seems like a fairly easy problem, but i'm not getting the book's answer.

    The sum from x=1 to infinity of 2x^2-1/3x^5+2x+1

    The book seems to expunge enough to make a reference series 1/x^3, which is a p-series. I just don't see how you can expunge that much..

    The question is as written in the book and asks: Use the Limit Comp. Test to determine the convergence or divergence of the series. No parenthesis are needed. the ^ implies something raised to a power.
    Hello,

    The parenthesis were for (2x^2-1)/(3x^5+2x+1) because it could be interpreted as 2x^2-(1/(3x^5+2x+1)) for example.

    For the p-series : divide the numerator & the denominator by x^2.
    Then, observe...
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  4. #4
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    Quote Originally Posted by Moo View Post
    Hello,

    The parenthesis were for (2x^2-1)/(3x^5+2x+1) because it could be interpreted as 2x^2-(1/(3x^5+2x+1)) for example.
    Thank you Moo...

    And...

    sometimes people don't put in parenthesis when they need to..they just leave them out...I'm a big fan of grouping symbols anyway. Just my little OCD I suppose.
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