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Homework Help: Solving a homogeneous first-order ordinary differential eqn

  1. Apr 20, 2016 #1
    1. The problem statement, all variables and given/known data
    dy/dx = (x+4y)2

    2. Relevant equations

    3. The attempt at a solution
    I substitute y=ux, where u is a function of x, and I'm not a ble to solve. My intention was to arrive at a seperable form, but I'm not achieving it.
  2. jcsd
  3. Apr 20, 2016 #2


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    Homework Helper

    Try the substitution u=x+4y.
  4. Apr 20, 2016 #3


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    Gold Member

    @Aceix Your problem is assuming your DE is homogeneous. Homogeneous in this sense means ##f(tx,ty) = f(x,y)##. That does't work for ##f(x,y)=(x-4y)^2##.
  5. Apr 20, 2016 #4
    Thanks a lot! I've got it now.
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