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Math Help - 2D probability integral question..

  1. #1
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    2D probability integral question..

    the question and solution
    after i they find the total interval of the total function
    i cant understand
    what they do with the graph and how they derive the integrals from it
    ?

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  2. #2
    MHF Contributor matheagle's Avatar
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    It looked like a minus sign, but this a product.
    You want to find the area under xy=k where 0<k<1.
    Your instructor looked at the complement, which is easier, since you only need one region instead of two.
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  3. #3
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    i cant understand this graph
    i understand the x1 and x2 are from 0 to 1 so we get a square
    but from where comes this curve?

    why we want " to find the area under xy=k where 0<k<1."
    Last edited by transgalactic; February 5th 2010 at 08:27 PM.
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  4. #4
    MHF Contributor matheagle's Avatar
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    it is called an hyperbola, let k=.5
    xy=.5 is y=.5/x.
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  5. #5
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    how do we know what area to calculate?
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  6. #6
    MHF Contributor matheagle's Avatar
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    As it states in your notes, it's xy<k. This is basic calc 3.
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  7. #7
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    how to we know that x1x2<t is bellow this line
    how to we know that x1x2>t is above this line
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  8. #8
    MHF Contributor matheagle's Avatar
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    Quote Originally Posted by transgalactic View Post
    how to we know that x1x2<t is bellow this line
    how to we know that x1x2>t is above this line
    it is a curve not a line
    pick a POINT, try (0,0)
    Last edited by matheagle; February 6th 2010 at 12:36 AM.
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  9. #9
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    if we take the curve y=1/x
    how to know that (0,0) is beloow y=1/x
    ?
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  10. #10
    MHF Contributor matheagle's Avatar
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    Quote Originally Posted by transgalactic View Post
    if we take the curve y=1/x
    how to know that (0,0) is beloow y=1/x
    ?
    draw xy=1, BUT isn't (0)(0)=0<1?
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  11. #11
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    thanks
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