1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    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!

Diff Equation

  1. Jun 21, 2009 #1
    1. The problem statement, all variables and given/known data
    y2dx -x(2x+3y)dy =0 I have to recognize the equation and solve it

    2. Relevant equations

    3. The attempt at a solution

    I did y2dx - (2x2+ 3yx) dy=0
    which is a homogeneous now
    after I substitude x=uy
    dx=udy + ydu

    I stuck here after the substitution

    y2udy+y3du - 2x2dy + 3yxdy=0

    please someone help if I am not in right direction from the begining.
  2. jcsd
  3. Jun 21, 2009 #2


    User Avatar
    Science Advisor

    I am more accustomed to write y= ux but your method is equivalent.
    Saying x= uy is the same as saying u= y/x. Divide your last equation by [itex]x^2[/itex] and see what you get!
  4. Jun 21, 2009 #3
    ok, thanks.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook