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Math Help - problem evaluating this integral

  1. #1
    Senior Member mollymcf2009's Avatar
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    problem evaluating this integral

    I worked through this integral using partial fractions, but I cannot for the life of me evaluate it. At least, my answer is not what webassign wants. I think I am not putting my logs together correctly. Anyway, can someone please evaluate this and show me final steps of combining logs, etc.

    Original problem:

    \int\limits^{9}_{7} \frac{x^3-5x^2-25}{x^3-5x^2} dx


    Here is my integral that I got using partial fractions, but that I cannot get my correct asnwer when I evaluate at the limits (I am assuming of course that I have the correct integral here):

    = \left[x + ln |x| - \frac{5}{x} - ln|x-5|\right] _{7}^{9}

    Thanks much!
    Last edited by mollymcf2009; February 15th 2009 at 11:03 PM.
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by mollymcf2009 View Post
    I worked through this integral using partial fractions, but I cannot for the life of me evaluate it. At least, my answer is not what webassign wants. I think I am not putting my logs together correctly. Anyway, can someone please evaluate this and show me final steps of combining logs, etc.

    Original problem:

    \int\limits^{9}_{7} \frac{x^3-5x^2-25}{x^3-5x^2} dx


    Here is my integral that I got using partial fractions, but that I cannot get my correct asnwer when I evaluate at the limits (I am assuming of course that I have the correct integral here):

    = \left[x + ln |x| - \frac{5}{x} - ln|x-5|\right] _{7}^{9}

    Thanks much!
    that integral is correct. so if you have a problem, it is from plugging in the limits, which is just arithmetic. just redo it.
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