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Homework Help: Volume Integral Help

  1. Jun 20, 2008 #1
    Volume Integral!!! Help!!!

    I need help with this:

    Find volume of figure bounded with surface (x^2+y^2+z^2+1)^2=8*(x^2+y^2)

    I tried Ostrogradsky, and spherical coordinate system with it, but I can't find boundaries...

    PLEASE!!! HELP ME!!!
  2. jcsd
  3. Jun 20, 2008 #2

    Tom Mattson

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    Please show us what you tried, then we'll help you. That's the policy here.
  4. Jun 20, 2008 #3


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    Welcome to PF!

    Hi DianaSagita ! Welcome to PF! :smile:

    (what's Ostrogradsky? :confused: )

    (oh, have a squared: ²)

    Hint: it's obviously cylindrically symmetric, so write x² + y² = r², to give:

    (r² + z² + 1)² - 8r² = 0. :smile:
  5. Jun 21, 2008 #4
    Thanks a lot. I did it! :)
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