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: Non-homogeneous 1st order diff equation

  1. Mar 16, 2010 #1
    1. The problem statement, all variables and given/known data
    Hi, I have to solve the following differential equation and while I can get the complimentary function I can't get the particular integral.


    2. Relevant equations

    How do I integrate the product of e^30t and alpha*cos(alpha*t) in order to find the particular integral?

    3. The attempt at a solution

    I've got y=Ce^(-30t) as the complimentary function but can get no further. Any help would be brilliant, thanks!
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Mar 16, 2010 #2


    User Avatar
    Homework Helper

    Integrate by parts


    dv=20sin(αt)+αcos(αt) dt
  4. Mar 16, 2010 #3
    Thanks, yeah I've been trying to do it by parts for the last little while but it get's very messy, very quickly whenever I have to integrate by parts twice. I'm rubbish at calculus, I end up with the same solution but it's obviously even near being correct.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook