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Math Help - Volume && Average Value Problems.

  1. #1
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    Volume && Average Value Problems.

    I'm having a little trouble with the following problems and I was wondering if someone could help out with either of them.


    1) A football has the shape of the solid generated by revolving the region bounded between the x-axis and the parabola
    y = (4R(x^2 - 1/4L^2)^2)/L^2 about the x-axis. Find its volume.


    2) Find the average value of f(x) = ex + e-x over the interval [ln , ln 2]


    Thanks!
    Last edited by Sotellme01; September 13th 2009 at 04:18 PM.
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  2. #2
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    Quote Originally Posted by Sotellme01 View Post
    I'm having a little trouble with the following problems and I was wondering if someone could help out with either of them.


    1) A football has the shape of the solid generated by revolving the region bounded between the x-axis and the parabola
    y = (4R(x^2 - 1/4L^2)^2)/L^2 about the x-axis. Find its volume.

    disk method ... \textcolor{red}{V = \pi \int_a^b [f(x)]^2 \, dx}


    2) Find the average value of f(x) = ex + e-x over the interval [ln , ln 2]

    \textcolor{red}{f_{avg} = \frac{1}{b-a} \int_a^b f(x) \, dx}
    ...
    Last edited by skeeter; September 14th 2009 at 08:06 AM. Reason: piece of pi added
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    <br />
\textcolor{red}{V = \int_a^b [f(x)]^2 \, dx}<br />
    Is that not supposed to be:


    <br />
V = \pi\int_a^b [f(x)]^2 \, dx<br />
    ?
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  4. #4
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    Quote Originally Posted by hjortur View Post
    Is that not supposed to be:


    <br />
V = \pi\int_a^b [f(x)]^2 \, dx<br />
    ?
    correct ... forgot my pi

    thanks
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