1. ## 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???

2. do u mean $\frac{(\cos x)^2}{e^x +1}$

3. yes exactly that

4. use integation by parts $\frac {v \frac{du}{dx} - u \frac {dv}{dx}} {v^2}$ where $v =(e^x +1)
,u= \cos^2 x$

5. can you be a bit more specific and write out every step

6. ok.. i will post it in about 10 mins, cos im still not used to using the LaTex math thing

7. 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

8. i differentiated the function instead of integrating

9. Originally Posted by razorfever

can this be integrated???
No.