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Math Help - second derivative

  1. #1
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    second derivative

    y = e^xsinx


    y'' = e^xcosx - e^xsinx

    correct? much appreciated.
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  2. #2
    MHF Contributor kalagota's Avatar
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    maybe not..

    what is your first derivative?
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  3. #3
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    Quote Originally Posted by kalagota View Post
    maybe not..

    what is your first derivative?
    the first derivative is

    y' = e^xsinx + e^xcosx
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  4. #4
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    Quote Originally Posted by jvignacio View Post
    the first derivative is

    y' = e^xsinx + e^xcosx
    Correct, and what is the second derivative? (Note your answer in your first post is not correct.)
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  5. #5
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    Quote Originally Posted by Chop Suey View Post
    Correct, and what is the second derivative? (Note your answer in your first post is not correct.)

    hmm is it.

    y'' = (e^xsinx + e^xcosx) + (e^xcosx - e^xsinx) ??
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  6. #6
    MHF Contributor kalagota's Avatar
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    yes indeed!

    and you should see that the terms with sin x cancel..
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  7. #7
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    Quote Originally Posted by kalagota View Post
    yes indeed!

    and you should see that the terms with sin x cancel..
    so it leaves e^xcosx + e^xcosx ??
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  8. #8
    MHF Contributor kalagota's Avatar
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    yes.. or simply 2e^x\cos x
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