How to Integrate Rational Functions with Unfactorable Denominators

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Homework Help Overview

The discussion revolves around integrating rational functions with unfactorable denominators, specifically the integrals of xdx/(x^2 + 4x + 5) and xdx/sqrt(x^2 + 4x + 13). Participants are exploring methods for integration and addressing challenges related to the problem setup.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss rewriting the integrals and suggest splitting them into simpler components. There are inquiries about methods such as completing the square and using partial fractions, along with questions about the original poster's attempts and understanding.

Discussion Status

The conversation is ongoing, with participants offering guidance on rewriting the integrals and exploring different approaches. There is a focus on ensuring that the original poster engages with the material rather than receiving direct answers.

Contextual Notes

Some participants emphasize the importance of not factoring the denominator, as it is unfactorable, and suggest completing the square instead. There are also language barriers noted, particularly regarding the terminology used in integration methods.

Hamid1
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Hi all.
can anyone integrate xdx/x^2+4x+5
and this one : xdx/sqrt(x^2+4x+13)

thank you and excuse me for english:)
 
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Are you interested in the answer or the method?
If you need just the answer then you can use "www.integrals.wolfram.com "
 
Yes,I want the method.
 
rewrite the numerator as (2x+4-4)/2.Try splitting the integral into two functions now.
 
Hamid1 said:
Yes,I want the method.
That's not the way it works here. We will help you with your homework, but we will not do it for you. You have to put some effort in.

What have you tried thus far?
 
rewrite the numerator as (2x+4-4)/2.Try splitting the integral into two functions now.
can you explain more?
That's not the way it works here. We will help you with your homework, but we will not do it for you. You have to put some effort in.
I have solved about 100 integrals but I can't do these two.I don't know the method.
thank you.
 
rewrite as integral of 1/2*( 2x+4/x^2+4x+5) -2*integral of (1/x^2+4x+5) . Now try to solve both of these integrals separately.
 
virus said:
rewrite as integral of 1/2*( 2x+4/x^2+4x+5) -2*integral of (1/x^2+4x+5) . Now try to solve both of these integrals separately.
Thank you.the first part is easy to solve but how can I solve the second part?
 
Hamid1 said:
Thank you.the first part is easy to solve but how can I solve the second part?
Use partial fractions.
 
  • #10
Hamid1 said:
Hi all.
can anyone integrate xdx/x^2+4x+5
and this one : xdx/sqrt(x^2+4x+13)

thank you and excuse me for english:)
Since you have "xdx" in the numerator- which should remind you of the derivative of x2, you should immediately think about getting the denominator in the form "x2- a" so you can substitute. In other words, start by completing the square in the denominator.
 
  • #11
Hootenanny said:
Use partial fractions.
Can you tell me how?Because I don't know english(partial fractions) very well.
 
  • #12
Hamid1 said:
Can you tell me how?Because I don't know english(partial fractions) very well.
Can you factorise the denominator and then split the fraction into two different fractions?
 
  • #13
No, the whole point of this problem is that you cannot factor the denominator. Complete the square instead.
 
  • #14
HallsofIvy said:
No, the whole point of this problem is that you cannot factor the denominator. Complete the square instead.
Whoops! I thought the denominator was (x2-4x-5).

*Slinks back off to physics*
 

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