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Separable DE

  1. Mar 12, 2006 #1
    How would I start this one? I tried dividing by y, but that does not work

    y'=xy/(1+x²)
     
  2. jcsd
  3. Mar 12, 2006 #2

    arildno

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    Why doesn't that work?
     
  4. Mar 12, 2006 #3
    Yeah why does dividing by y not work?
     
  5. Mar 12, 2006 #4
    Here's what I did:

    1/y y' = x/(1+x²)
    ln y = 1/2 ln (1+x²)+c
    y = ce^(1/2 ln(1+x²))

    Answer's supposed to be: c*sqrt(1+x²)
     
  6. Mar 12, 2006 #5
    Yeah, ok and how is that different from what you had? Just simplify your expression with the properties of logs.
     
  7. Mar 12, 2006 #6
    Nevermind. I get it now. Thank you :)
     
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