Can anyone here explain how did he get it.

  • Context: Undergrad 
  • Thread starter Thread starter sarah22
  • Start date Start date
  • Tags Tags
    Explain
Click For Summary

Discussion Overview

The discussion revolves around a mathematical query regarding the integration of a function involving the exponential function and a substitution method. Participants are trying to clarify the steps taken in a specific integral transformation.

Discussion Character

  • Technical explanation, Homework-related

Main Points Raised

  • One participant expresses confusion about the transformation from \((e^x)^2\) to \(u\) and why the square is not present in the final expression.
  • Another participant suggests inserting an integral expression \(\int\frac{u}{u+3}\,du\) to clarify the transformation.
  • A later reply explains the substitution process, detailing how \(u = e^x\) leads to the integral being simplified to \(\int \frac{u}{u+3}du\) after correcting for \(dx\).
  • One participant acknowledges their oversight regarding the \(dx\) part and expresses satisfaction with the clarification received.

Areas of Agreement / Disagreement

Participants appear to resolve the initial confusion regarding the integral transformation, but the discussion reflects an individual misunderstanding rather than a broader disagreement.

Contextual Notes

Some assumptions about the substitution method and the handling of differential elements may not be fully articulated, leading to potential gaps in understanding for those unfamiliar with the process.

Who May Find This Useful

Students or individuals studying calculus, particularly those interested in integration techniques and substitution methods.

sarah22
Messages
26
Reaction score
0
I thought it is (e^x)^2 with u = e^x
so it should be u^2 but he get only u without a square. Can anyone here explain it.

The red box.
http://img6.imageshack.us/img6/3272/whatj.png
 
Last edited by a moderator:
Physics news on Phys.org
Put in between the red box and the previous line:
\int\frac{u}{u+3}\,du
 
sarah22 said:
I thought it is (e^x)^2 with u = e^x
so it should be u^2 but he get only u without a square. Can anyone here explain it.

The red box.
http://img6.imageshack.us/img6/3272/whatj.png
[/URL]
Hi
Because \int \frac{(e^x)^2}{e^x+3}dx\rightarrow u=e^x\Rightarrow du=e^xdx \Rightarrow dx=\frac{du}{e^x}
So,

\int \frac{u^2}{u+3}\frac{du}{u}=\int \frac{u}{u+3}du
 
Last edited by a moderator:
LMAO. I forgot the dx part. woah. Laziness is here.

Anyway, Thanks. I got it now. (^_^)
 
sarah22 said:
LMAO. I forgot the dx part. woah. Laziness is here.

Anyway, Thanks. I got it now. (^_^)

:smile:
 

Similar threads

  • · Replies 19 ·
Replies
19
Views
5K
  • · Replies 16 ·
Replies
16
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 4 ·
Replies
4
Views
2K