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Is there enough information?

  1. Jul 20, 2006 #1
    Hi, I have been thinking recently about integrating something with 3 parts such as:

    [tex]I=\int_{0}^{\infty}f(x)\ast g(x)\ast h(x)\ast dx[/tex]

    If I is an unknown that we are trying to find and we know what J and K are where:

    [tex]J=\int_{0}^{\infty}f(x)\ast g(x)\ast dx[/tex]


    [tex]K=\int_{0}^{\infty}f(x)\ast h(x)\ast dx[/tex]

    Is there enough information to find I? (Note how we cannot get rid of or change the limits).

  2. jcsd
  3. Jul 20, 2006 #2

    Just to add, we assume that each function is easy to differentiate or integrate by itself but the three functions multiplies is too difficult.

  4. Jul 20, 2006 #3


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    Homework Helper

    If your question is, can you express I in terms of J and K for arbitrary f,g,h, the answer is no. One easy was to see this is by letting f=1. You can still integrate by parts if you use something like u=f(x)g(x), du=h(x)dx.
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