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anonymous

  • 5 years ago

evaluate the integral of e^(3x)cos(4x)dx

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  1. anonymous
    • 5 years ago
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    integration by parts where u=cos(4x) and dv=e^3x

  2. anonymous
    • 5 years ago
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    \[\int\limits_{}^{}e ^{3x}(e ^{i4x}+e ^{-i4x})dx/2\]\[e ^{(3+4i)x}/(3+4i)+e ^{(3-4i)}/(3-4i)\]

  3. anonymous
    • 5 years ago
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    or Euler's Identity which ever one comes easier to you..LOL

  4. anonymous
    • 5 years ago
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    the expression will be divided by 2.

  5. anonymous
    • 5 years ago
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    now you can just solve to get a ans.e^3x(3cos4x+4sin3c)/25+c where c is the integration constant.

  6. anonymous
    • 5 years ago
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    \[\frac{1}{25} e^{3 x} (3 \text{Cos}[4 x]+4 \text{Sin}[4 x]) \]from Mathematica 8

  7. anonymous
    • 5 years ago
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    wow, u are so smart, you can copy answers out of a software package :/

  8. anonymous
    • 5 years ago
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    thank u :) u forgot the plus C robtobey

  9. anonymous
    • 5 years ago
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    see these videos if you want. http://www.youtube.com/watch?v=-ikhaXsiJU8&feature=related http://www.youtube.com/watch?v=XO6b4zhZgOs&feature=related

  10. anonymous
    • 5 years ago
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    to do it algebraically involves two steps of integration by parts

  11. anonymous
    • 5 years ago
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    I think they most likely wanted it done algebraically

  12. anonymous
    • 5 years ago
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    first video does it algebraically ( which is most likely the way they want you to do it

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spraguer (Moderator)
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