1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Differential Equation Method Question

  1. Mar 3, 2010 #1
    dy/dx = (y-x)/(y+x)

    I am suppose to solve this equation using substitution, but isn't it possible to solve this equation an easier way since it is an exact equation?

    (y+x)dy - (y-x)dx = 0
     
  2. jcsd
  3. Mar 3, 2010 #2

    Gib Z

    User Avatar
    Homework Helper

    It's not an exact ODE. The form is [tex]P(x,y)dy + Q(x,y) dx = 0[/tex] for exact ODE's, you didn't bring the negative factor in.
     
  4. Mar 3, 2010 #3
    [tex]\frac{dy}{dx}=\frac{y-x}{y+x}=\frac{y}{y+x}-\frac{x}{y+x}[/tex]

    Use the substitution [tex]v=x+y[/tex].
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook