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Undetermined coefficients help

  1. May 3, 2008 #1
    Hi, new here, im looking for some help on this homework problem. pretty sure you need to separate yp into 2 parts?

    anyways, use method of undetermined coeff. to solve

    y" + y = x*cos(x) - cos(x)

  2. jcsd
  3. May 3, 2008 #2


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    Hi brungus and welcome to PF,

    I'm assuming that you've found the homogeneous solution. For the particular solution, notice that we have a product of two functions of x. How does one usually differentiate a product of two functions?

    Also for future reference, we have Homework Forums where you can post all your textbook questions :smile:.
  4. May 4, 2008 #3


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    Why have you not shown any work? In particular, what do you get for the general solution to the corresponding homogeneous equation?
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