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Homework Help: Derivative of a function, Is my answer correct?

  1. Oct 25, 2009 #1
    1. The problem statement, all variables and given/known data
    y=e^9Θsin(8Θ)


    2. Relevant equations



    3. The attempt at a solution
    dy/dΘ=e^9Θ(sin(8Θ)+8cos(8Θ))
     
  2. jcsd
  3. Oct 25, 2009 #2
    [Edit] I didn't catch the missing 9; sorry about that.
     
    Last edited: Oct 25, 2009
  4. Oct 25, 2009 #3

    lanedance

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    is that (using t for theta)

    y=e^(9t.sin(8t)) or y=(e^(9t)).sin(8t)?
     
  5. Oct 25, 2009 #4
    Ugh, it said incorrect...
     
  6. Oct 25, 2009 #5

    lanedance

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    if it is
    y=(e^(9t)).sin(8t)

    i think you should get an extra factor of 9
    y'=(e^(9t)).(9sin(8t)+ 8cos(8t))
     
  7. Oct 25, 2009 #6

    Pengwuino

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    Gold Member

    Lanedance is right, you get that factor of 9 when taking the exponential derivative.
     
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