1. Not finding help here? Sign up for a free 30min 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!

A tricky 2nd ODE nonhomo delta=0 help needed

  1. May 11, 2009 #1
    1. The problem statement, all variables and given/known data
    solve the initial value problem:
    y''+8.4y'+17.64y=e-4.2x
    y(0)=1, y'(0)=1

    y(x)=?


    2. Relevant equations
    y=yc+yp


    3. The attempt at a solution

    The way I tried to achieve is to solve the corresponding homo equation first:
    y''+8.4y'+17.64y=0, which gives yc;
    yc=c1e-4.2x+c2e-4.2xx

    Then try to find yp, generally I would assume a yp=Ae-4.2x, but from the yc got above, clearly yp=Ae-4.2x or yp=Ae-4.2xx is not good. If I add one more 'x' in yp assumption,in which it seems A has to be 0, which is not right either....

    Any idea? Or I made some mistake?

    Meric.
     
  2. jcsd
  3. May 11, 2009 #2

    Mark44

    Staff: Mentor

    Assuming that the work you show is correct, yp = Ax2e-4.2x is the right choice. Plug it into your DE and solve for A.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: A tricky 2nd ODE nonhomo delta=0 help needed
  1. Tricky ODE (Replies: 1)

Loading...