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Math Help - Challenging Integral

  1. #1
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    Challenging Integral

    \int e^x cosx dx

    Can someone walk me through this integral?
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  2. #2
    Master Of Puppets
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    Do you know integration by parts?

    If so do this twice.
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  3. #3
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    After integrating twice I get:

    e^x sinx + e^x cosx - \int cosx e^x

    Then what do I do?
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  4. #4
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    Quote Originally Posted by penguinpwn View Post
    After integrating twice I get:

    e^x sinx + e^x cosx - \int cosx e^x

    Then what do I do?
    \int e^x \cos{x} \, dx = e^x \sin{x} + e^x \cos{x} - \int \cos{x} \cdot e^x \, dx

    2\int e^x \cos{x} \, dx = e^x \sin{x} + e^x \cos{x} + C

    finish up
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  5. #5
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    Woah, did not know that trick.

    Thanks a ton!
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