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Math Help - hard integration

  1. #1
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    hard integration

    how do i integrate

    (cos x)^2 / (e^x) + 1

    i tried integration by parts but that made it even harder and i can't seem to figure out any trig substitution, can this be integrated???
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  2. #2
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    do u mean  \frac{(\cos x)^2}{e^x +1}
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  3. #3
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    yes exactly that
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  4. #4
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    use integation by parts \frac {v \frac{du}{dx} - u \frac {dv}{dx}} {v^2} where v =(e^x +1) <br />
,u= \cos^2 x
    Last edited by iLikeMaths; March 12th 2009 at 04:46 PM.
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  5. #5
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    can you be a bit more specific and write out every step
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  6. #6
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    ok.. i will post it in about 10 mins, cos im still not used to using the LaTex math thing
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  7. #7
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    this is the same answer as i got ... i thought it was wrong cause it seemed too big

    now do you know how i can find the lim as x goes to infinity of this expression
    this is involving a series problem in order to find the upper error bound and the remainder
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  8. #8
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    i differentiated the function instead of integrating
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  9. #9
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    Quote Originally Posted by razorfever View Post

    can this be integrated???
    No.
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