Integrate x/(x^2-2x+5): Clarifying Steps

  • Thread starter Thread starter Azureflames
  • Start date Start date
  • Tags Tags
    Integral
Click For Summary
SUMMARY

The integral of x/(x^2-2x+5) dx can be solved by completing the square in the denominator to obtain x/((x-1)^2+4). The solution involves substituting u = x^2 - 2x + 5, leading to the integral (1/2)integral( (du-2)/u ). This is split into two parts: (1/2)ln(x^2 - 2x + 5) and -(1/2)integral(2/(x^2 - 2x + 5). The final answer is (1/2)ln(x^2 - 2x + 5) - (1/2)arctan((x-1)/2) + C.

PREREQUISITES
  • Understanding of integral calculus
  • Knowledge of completing the square
  • Familiarity with substitution methods in integration
  • Basic understanding of logarithmic and arctangent functions
NEXT STEPS
  • Study integration techniques involving substitution
  • Learn about completing the square in polynomial expressions
  • Explore the properties of logarithmic and arctangent functions
  • Review partial fraction decomposition methods for rational functions
USEFUL FOR

Students studying calculus, particularly those focusing on integration techniques, as well as educators looking for examples of solving integrals involving rational functions.

Azureflames
Messages
3
Reaction score
0

Homework Statement



Hi, I'm trying to take the integral of x/(x^2-2x+5) dx but I'm not sure what to do.

Homework Equations





The Attempt at a Solution



I started by completeing the square in the denominator giving me the integral of x/((x-1)^2+4)) dx but I am not sure where to go from there. I have the correct answer for it but I need to understand the steps involved getting there.

EDIT: Okay, after spending a decent amount of time on this problem I finally look for some place to get help, and 5 minutes later I think I come up with a solution.

First, I set u = x^2 - 2x +5, du/2 - 2/2 = x. Substituted back in which gave me (1/2)integral( (du-2)/u ) which I then split into (1/2)integral(du/u) - (1/2)integral(2/u).

Taking the integral of the first part gave me (1/2)ln(x^2 - 2x +5). For the second half, I substitued the u values back into the equation which gave me: -(1/2)integral(2/(x^2 - 2x + 5). I completed the square in the denominator which gave me -integral( 1/((x-1)^2+4 ).

Integrating that part of the equation gives me -(1/2)arctan((x-1)/2).

So my final answer is (1/2)ln(x^2 - 2x +5) - (1/2)arctan((x-1)/2) + C. Can someone please confirm my steps? Sorry if my work is hard to follow. I wasn't sure how to make the proper symbols and my time is short :)
 
Last edited:
Physics news on Phys.org
That's right.
 
Hell, that seemed clever(or I suck)

I would've done partial fraction decomposition, and heaven knows NO ONE likes doing that
 

Similar threads

  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 105 ·
4
Replies
105
Views
11K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 22 ·
Replies
22
Views
3K
  • · Replies 27 ·
Replies
27
Views
3K
  • · Replies 12 ·
Replies
12
Views
2K
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K