Solving Integral Using Integration by Parts

Click For Summary
SUMMARY

The discussion focuses on solving the integral of ln(x+3) using integration by parts. The user correctly identifies u=ln(x+3) and dv=dx, leading to the equation integral ln(x+3) = xln(x+3) - integral x/(x+3). To simplify the integral of x/(x+3), participants recommend performing polynomial long division or rewriting the integrand as a sum of simpler fractions, specifically as integral (x+3)/(x+3) dx - 3 integral (1/(x+3)) dx. These methods lead to a more straightforward evaluation of the integral.

PREREQUISITES
  • Understanding of integration techniques, specifically integration by parts.
  • Familiarity with polynomial long division.
  • Knowledge of basic logarithmic functions and their properties.
  • Ability to manipulate integrals involving rational functions.
NEXT STEPS
  • Practice additional problems using integration by parts with different functions.
  • Study polynomial long division techniques in detail.
  • Explore the properties of logarithmic integrals.
  • Learn about partial fraction decomposition for simplifying integrals.
USEFUL FOR

Students and educators in calculus, mathematicians, and anyone looking to enhance their skills in solving integrals using integration techniques.

Frillth
Messages
77
Reaction score
0
I'm doing a problem where I'm supposed to use integration by parts. I have:

Integral ln(x+3)dx

u=ln(x+3) dv=dx
du=1/(x+3) v=x

integral ln(x+3) = xln(x+3) - integral x/(x+3)

That's as far as I've gotten. I know that I should be able to find the integral of x/(x+3) fairly easily, but I just completely forgot how to do it. Could somebody please lend me a hand?
 
Physics news on Phys.org
Do the long division of x / (x + 3). Then you should have an easily integrable result.
 
Another option is this: Rewrite your numerator as
[tex]\int \frac{x + 3 - 3}{x + 3} dx[/tex] . Then, you can have two integrals, [tex]\int \frac{x+3}{x+3} dx -3 \int \frac{1}{x+3} dx[/tex]

That should be easier to evaluate. Adding the +3 -3 is the same as adding zero, so it's okay.
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 26 ·
Replies
26
Views
2K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
2
Views
1K
  • · Replies 22 ·
Replies
22
Views
3K
  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K