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Math Help - Strange equation

  1. #1
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    Strange equation

    Hello

    I am new to this forum. I think that you are doing a very good job here helping people solve their problems !!!!

    In few days i have one of my final course exam (I will graduate) and i have some questions that concerns me

    One of them is this :

    y'''' * y'''= 1

    I had an idea to put y'''=u , y''''=u' but it didn't worked

    How can i solve this ???

    Thanks in advance
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  2. #2
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    That's the same as vdv=dx isn't it? I mean isn't y'''' the derivative of y'''?
    Same dif if is was yy'=1 or y'y'' and so forth.
    Last edited by shawsend; May 24th 2010 at 11:34 AM. Reason: added dx to equation
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  3. #3
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    So how is this equation can be solved ???
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  4. #4
    Behold, the power of SARDINES!
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    Quote Originally Posted by iratus View Post
    So how is this equation can be solved ???

    Your orginal idea will work

    let u=y''' \implies u'=y^{(4)} this gives the equation

    \frac{du}{dx}u=1 \iff udu=dx \iff u^2=2x+C \iff u=\sqrt{2x+C}

    Now u=y''' is just integrate the above three times to recover the function y.
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