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Homework Help: DE method help

  1. May 9, 2006 #1
    What approach should be used to solve the following DE:

    dy/dx= (-2x+5y)/(2x+y)

    Find an integrating factor and solve it as an excact equation?

    Thanks.
     
  2. jcsd
  3. May 10, 2006 #2

    Tide

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    See what happens if you define a new variable: z = y/x
     
  4. May 10, 2006 #3
    Thanks!

    Right, I get

    1/[(-2+5z)/(2+z)-z] dz = (1/x) dx

    so

    3ln(z-1) -4ln(z-2) = lnx +c

    and

    3ln(y/x -1) -4ln(y/x-2)-lnx = c

    ?
     
  5. May 10, 2006 #4

    Tide

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    Good - but I got different signs on my first try. You should recheck.
     
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