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: Second Order ODE

  1. Jan 7, 2012 #1
    Hi. I am new to differential equations. This is probably pretty easy but I don't quite understand how to do it yet.

    The equation is y^4 -3y'' -4y = 0.

    I can figure out what class of equation it is. I can write it in the form y'' = F(y), but I am not really sure how to solve it.
     
  2. jcsd
  3. Jan 7, 2012 #2
    Actually I think the problem is y'''' - 3y'' -4y. But I am still not sure what to do.
     
  4. Jan 8, 2012 #3
    Sure it is y'''' - 3y'' -4y = 0 because dasy to solve.
    Solving y^4 - 3y'' -4y =0 is possible, but hard. It involves elliptic integral.
     
  5. Jan 11, 2012 #4
    This is ODE with constant coefficients..

    Suppose that the solution is y=e^rx, than solve it!

    i find that r=2, r=-2, r=i, r=-i

    which means that

    complementary solution of eqn is y=c_1*e^2x + c_2*e^-2x + c_3(sinx) + c_4(cosx)
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook




Loading...