Integration Help

  • Thread starter negatifzeo
  • Start date
  • #1
66
0

Homework Statement


[itex]
\int {\frac {1}{\sqrt {{e^{x}}+1}}} dx
[/itex]


The Attempt at a Solution



I tried integration by parts, using [itex]{\frac {1}{\sqrt {{e^{x}}+1}}}[/itex] as u and dx as dv. This seemed to make the problem more complicated. Using e^x+1 as a u substitution won't work either. Any help getting on the right path would be greatly appreciated!

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
rock.freak667
Homework Helper
6,223
31
You could try hyperbolic trig sub. such as ex=sinhu
 
  • #3
66
0
I don't know what hyperbolic trig sub. is yet. We've just gotten to integration by parts.
 
  • #4
rock.freak667
Homework Helper
6,223
31
I don't know what hyperbolic trig sub. is yet. We've just gotten to integration by parts.

Have you done normal trig substitutions? As ex=tan2u looks like it would work out fine
 
  • #5
66
0
Nope. Maybe it's a problem I'm just supposed to try and not succeed at.
 
  • #6
rock.freak667
Homework Helper
6,223
31
Nope. Maybe it's a problem I'm just supposed to try and not succeed at.

Did you learn partial fractions yet? If you did try putting [itex]u^2=e^x+1[/itex] and post back what you tried.
 
  • #7
66
0
I'm not sure of the procedure when using that technique. if u^2=e^x+1, then does the integral become 1/u? Then the answer would just be ln(u)... I dont think thats right
 
  • #8
rock.freak667
Homework Helper
6,223
31
I'm not sure of the procedure when using that technique. if u^2=e^x+1, then does the integral become 1/u? Then the answer would just be ln(u)... I dont think thats right

u^2=e^x +1
then 2u du =e^x dx and e^x=?
and so dx =?
 
  • #9
66
0
This problem is driving me nuts. There was a typo earlier, it's actually e^x-1.

Expanding on what you said, if u^2=e^x-1
2udu=e^xdx and dx=(2udu/e^x). Moving all of this stuff around is just fine and dandy but I don't know where to put it back in.
 

Related Threads on Integration Help

  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
5
Views
1K
  • Last Post
Replies
3
Views
777
  • Last Post
Replies
5
Views
1K
  • Last Post
Replies
9
Views
719
  • Last Post
Replies
5
Views
2K
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
4
Views
1K
  • Last Post
Replies
6
Views
962
  • Last Post
Replies
5
Views
1K
Top