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Math Help - FTC part 2 help

  1. #1
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    FTC part 2 help

    (5x)Σcos(x) cosu^4 du=

    I got 5cos(20x^3)+cos(4cos(x)^3)(sin(x)) but it is incorrect. can someone explain to me why this is incorrect help me correct it?
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  2. #2
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    Re: FTC part 2 help

    Hey rhcprule3.

    What does the sigma refer to? Is it a summation and if so, what are the limits and dummy indices?
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  3. #3
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    Re: FTC part 2 help

    With that "du" I'm inclined to believe you mean an integration with respect to u But then what about the "5x" and "cos(x)"? Do you mean, the simplest way I can interpret this,
    5x cos(x) \int cos^4(u) du? To integrate that you could use cos^2(u)= (1/2)(1+ cos(2u)), twice. But I cannot imagine where you could have got that "20" inside the cosine, much less the cube! So perhaps I am misunderstanding completely.
    Last edited by HallsofIvy; November 22nd 2013 at 04:19 PM.
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