How to Integrate ln(x+1)/x^2 using Partial Fractions

  • Thread starter Thread starter nameVoid
  • Start date Start date
  • Tags Tags
    Integral
Click For Summary

Homework Help Overview

The discussion revolves around the integration of the function ln(x+1)/x^2, with participants exploring various methods including integration by parts and partial fractions. The problem falls under the subject area of calculus, specifically focusing on integration techniques.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants suggest using integration by parts and express concerns about the application of partial fractions. There are attempts to rewrite the integral in different forms, and questions arise regarding the correctness of the steps taken, particularly in relation to the coefficients in the partial fraction decomposition.

Discussion Status

The discussion is ongoing, with participants providing different approaches and questioning the validity of certain steps. Some guidance has been offered regarding integration by parts, while others are examining the implications of the partial fraction method. There is no clear consensus on the correct approach yet.

Contextual Notes

Participants are navigating through potential errors in their calculations and the assumptions made in their methods. The presence of the natural logarithm function in the integration process is a point of contention, particularly in the context of partial fractions.

nameVoid
Messages
238
Reaction score
0
[tex] \int \frac{ln(x+1)}{x^2}dx[/tex]
[tex] u=x+1[/tex]
[tex] \int\frac{lnu}{(u-1)^2}du[/tex]
[tex] \int \frac{A}{u-1}+\frac{B}{(u-1)^2}du[/tex]
[tex] lnu=A(u-1)+B[/tex]
[tex] B=0,A=ln2[/tex]
[tex] \int \frac{ln2}{u-1}du[/tex]
[tex] ln2ln|x|+C[/tex]
 
Physics news on Phys.org
You have to do integration by parts.
Int[ln(x+1)/x^2] = ln(x+1)*intg(1/x^2) - Intg{[Intg(1/x^2)*d/dx[ln(x+1)]}
Now proceed.
 
where is the error
 
I = -1/x*ln(x+1) - int[(-1/x)*1/(x+1)]
= -1/x*ln(x+1) + int(1/x) - int1/(x+1)
Now find the integration.
In your partial factor, there is no ln function in the right hand side. So you can't equate the coefficients.
 

Similar threads

  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 105 ·
4
Replies
105
Views
11K
  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 22 ·
Replies
22
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
Replies
3
Views
2K
Replies
5
Views
2K
  • · Replies 15 ·
Replies
15
Views
2K