Integration problem

  • #1
438
0

Homework Statement



evaluate [tex]\int \frac{1}{x^2+1} dx[/tex]


Homework Equations





The Attempt at a Solution



This cant be [tex]\frac{\ln x^2+1}{2x}[/tex] , my first thought on this .

Then , i tried partial fraction , it didn't work either .
 

Answers and Replies

  • #2
35,132
6,878


Homework Statement



evaluate [tex]\int \frac{1}{x^2+1} dx[/tex]


Homework Equations





The Attempt at a Solution



This cant be [tex]\frac{\ln x^2+1}{2x}[/tex] , my first thought on this .

Then , i tried partial fraction , it didn't work either .
Your first thought led you to try an ordinary substitution, u = x^2 + 1. This won't work, though, because du = 2xdx, so there's no way to change the given integrand to du/u.

If you know a derivative formula for which d/dx(something) = 1/(x^2 + 1) then that will be helpful in this problem. If you don't know or don't remember such a formula, a trig substitution will be the way to go, with tan u = x/1.
 

Related Threads on Integration problem

  • Last Post
Replies
14
Views
2K
  • Last Post
Replies
3
Views
462
  • Last Post
Replies
2
Views
587
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
9
Views
644
  • Last Post
Replies
7
Views
1K
  • Last Post
Replies
2
Views
830
  • Last Post
Replies
8
Views
1K
  • Last Post
Replies
5
Views
941
Top