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Math Help - Volume of a solid

  1. #1
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    Volume of a solid

    What is the volume of:
    y=square root(x), y=1, x=4
    revolved about the x-axis?
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  2. #2
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    Use the disc method. We create a disc by making a cross section perpendicular to the x-axis. The volume is then given by \int_a^b A(x) dx where A(x) is the area of our disc and x= a, \ b are our bounds.

    More here: Volume with Rings
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  3. #3
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    is that the same as
    V=(pie)interval from a to b((f(x)^2)-(g(x)^2) dx
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  4. #4
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    Yes. What is our f(x) and g(x) in this case?
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  5. #5
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    f(x)=square root of x
    g(x)=1
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  6. #6
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    So is the answer 9pie/2
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  7. #7
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  8. #8
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    awesome thanks
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  9. #9
    Senior Member DeMath's Avatar
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    Also see picture

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