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Math Help - Change of Variables

  1. #1
    Junior Member
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    Change of Variables

    Tricky....

    Reduce u'' + (ax+b)u = 0 to u'' + tu = 0 by a suitable change of variables.
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  2. #2
    Junior Member
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    Let ax+b = t, then by differenciating u(x) with respect to t twice using the chain rule you will get (a^2)u'' + tu = 0. Is this what you wanted?
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  3. #3
    Member Mauritzvdworm's Avatar
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    this can surely not be the whole story, since by just chosing t=ax+b your problem will already be solved...

    can you give a bit more information?

    I suppose it should read like this:

    \frac{d^{2}u(x)}{dx^{2}}+(ax+b)u(x)=0

    and you want to make a substitution such that you end up with

    \frac{d^{2}u(z)}{dz^{2}}+tu(z)=0

    ??
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