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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- Mar 12th 2009, 02:05 PMrazorfeverhard 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??? - Mar 12th 2009, 02:11 PMiLikeMaths
do u mean $\displaystyle \frac{(\cos x)^2}{e^x +1} $

- Mar 12th 2009, 02:29 PMrazorfever
yes exactly that

- Mar 12th 2009, 02:49 PMiLikeMaths
use integation by parts $\displaystyle \frac {v \frac{du}{dx} - u \frac {dv}{dx}} {v^2}$ where $\displaystyle v =(e^x +1)

,u= \cos^2 x$ - Mar 12th 2009, 03:30 PMrazorfever
can you be a bit more specific and write out every step

- Mar 12th 2009, 03:32 PMiLikeMaths
ok.. i will post it in about 10 mins, cos im still not used to using the LaTex math thing

- Mar 12th 2009, 03:54 PMrazorfever
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 - Mar 12th 2009, 03:56 PMiLikeMaths
i differentiated the function instead of integrating

- Mar 12th 2009, 06:55 PMKrizalid