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Volume of a solid bound by four surfaces

  1. Oct 25, 2015 #1
    1. The problem statement, all variables and given/known data
    Compute the volume of the solid bounded by the four surfaces x+z=1,x+z=−1,z=1−y2,z=y2−1

    2. Relevant equations
    Fubini's theorem?

    3. The attempt at a solution
    I have tried to visualize this solid and define the limits; when I attempted to integrate by dxdzdy (in that order), I set the limits for the first integral as -z-1 to -z+1, the second integral as y^2-1 to 1-y^2, and third integral as -1 to 1, but the I'm not getting a value due to the second integral evaluating as zero.

    I feel almost certain that the problem mainly has to do with defining the correct limits and order of integration, but I'm having a bit of trouble here.

    Thanks.
     
  2. jcsd
  3. Oct 25, 2015 #2

    mfb

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    Staff: Mentor

    How can the second integral be zero? Some sign error?
    The order of integrals is useful.
     
  4. Oct 25, 2015 #3
    Because y2-1=-(1-y^2) and there are no y terms after the first integral, the integral equals 0.
     
  5. Oct 25, 2015 #4

    mfb

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    Staff: Mentor

    If you integrate f(y)=1 from y=-5 to y=5, is the result 0 - or maybe 10?
     
  6. Oct 25, 2015 #5
    Wow. I can't believe that I made such a dumb mistake. I stared at it for at least 10 min straight.

    Thanks for putting up with such a trivial problem. X(
     
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