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Math Help - Wolfram Alpha miscalculation

  1. #1
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    Wolfram Alpha miscalculation

    I'm trying to confirm my solution to the following double integral on Wolfram Alpha.

    The double integral is evaluated properly only if the outer integral is indefinite.
    Wolfram Alpha miscalculation-2-1a.gif

    Wolfram Alpha miscalculation-2-1b.gif



    The moment I try to define bounds for the second integral it breaks down:
    Wolfram Alpha miscalculation-2-2.gif


    Any ideas why this is happening? Should I input differently?

    Here's the link to my second entry if you want to try it out.
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  2. #2
    Senior Member roninpro's Avatar
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    I tried typing in the Mathematica code:

    Code:
    Integrate[Integrate[x+y,{y,x^2,x}],{x,.25,.75}]
    I got the same output as you. I think that you should file a bug report with the support team.

    For now, I would do one integral at a time.
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  3. #3
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    The problem is that multiple integrals should be input with a single "integrate" command. You'll find this input works:

    integrate (x+y) dy dx, y=x^2 to x, x=0.25 to 0.75

    (The same applies to Mathematica. See the examples given here.)
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  4. #4
    Senior Member roninpro's Avatar
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    Ah, I wasn't aware that I could do that. I've always written all of the integrals without any problem.
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  5. #5
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    http://www.wolframalpha.com/input/?i...29^%281%2F2%29

    Look when makes the replacement u=x^2

    Shouldn't the denominator be \sqrt[ ]{u} when replaces?

    Use the "show steps" option.

    Srry, it was a miss interpretation from my part. Multiplies and divides for 2x
    Last edited by Ulysses; July 5th 2010 at 05:52 AM.
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