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Power series method of solving ODE

  1. Jun 16, 2009 #1
    Please can somebody help me with this problem

    y" + y' + sin^2(x)y - 2sinx = 0

    I used power series method and i used the macclurin expresion for sinx but i was not able to get a recurrence formular.
     
  2. jcsd
  3. Jun 16, 2009 #2
    I did not check it but did you try plugging in

    [itex]\sin^2(x) = \frac{1-\cos(2x)}{2}[/itex]

    and expand your series again?
     
  4. Jun 16, 2009 #3

    HallsofIvy

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    Very nice suggestion.
     
  5. Jun 17, 2009 #4
    I cann't get it that way. I think i need to use the macclurin series so that sin^2 will be in terms of x. Pls any other suggestion?
     
  6. Jun 17, 2009 #5

    HallsofIvy

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    I have no idea what you mean by "i need to use the macclurin series so that sin^2 will be in terms of x". Of course [itex]sin^2 x[/itex] is in terms of x- that has nothing to do with a series! And trambolin did not mean that you shouldn't use MacLaurin series but that it is far easier to write a MacLaurin series for cos(2x) than to have a MacLaurin series, for sin(x) squared!
     
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