Results 1 to 2 of 2

Math Help - No idea where to start

  1. #1
    Junior Member
    Joined
    Aug 2009
    Posts
    29

    No idea where to start

    Solve in general

     \frac{d^2y}{dx^2}+2\frac{dy}{dx}=1+e^{-2x}
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Rhymes with Orange Chris L T521's Avatar
    Joined
    May 2008
    From
    Santa Cruz, CA
    Posts
    2,844
    Thanks
    3
    Quote Originally Posted by Karl Harder View Post
    Solve in general

     \frac{d^2y}{dx^2}+2\frac{dy}{dx}=1+e^{-2x}
    Solve the homogeneous equation first:

    y^{\prime\prime}+2y^{\prime}=0\implies r^2+2r=0\implies r=0 or r=-2.

    So we have y_c=c_1+c_2e^{-2x}.

    Now, we solve the non-homogeneous equation by method of undetermined coefficients.

    Take y_p=Ax+Be^{-2x}+Cxe^{-2x}, substitute it into the differential equation, and then solve for the unknown coefficients.

    Your final answer will be of the form y=y_c+y_p=\dots

    Can you take it from here?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. No idea where to start
    Posted in the Algebra Forum
    Replies: 2
    Last Post: August 3rd 2010, 11:06 AM
  2. matlab for loop help.. NO idea where to start..
    Posted in the Math Software Forum
    Replies: 1
    Last Post: March 16th 2010, 07:20 PM
  3. Complex number.. need an idea to start..
    Posted in the Calculus Forum
    Replies: 7
    Last Post: November 29th 2009, 02:59 PM
  4. Replies: 4
    Last Post: April 13th 2009, 05:26 PM
  5. [SOLVED] No idea where to start!
    Posted in the Algebra Forum
    Replies: 11
    Last Post: July 25th 2008, 09:44 AM

Search Tags


/mathhelpforum @mathhelpforum