How Do You Integrate 1/√(x^3 + x^2 + x + 1) dx?

  • Context: Undergrad 
  • Thread starter Thread starter askor
  • Start date Start date
  • Tags Tags
    Dx Integrate
Click For Summary
SUMMARY

The discussion focuses on integrating the function ##\frac{1}{\sqrt{x^3 + x^2 + x + 1}} \, dx##, highlighting the use of elliptic integrals. Participants suggest rewriting the polynomial as ##(x^2+1)(x+1)## and using substitutions such as ##x^2+1=u##. The conversation emphasizes the complexity of the integral, noting that it falls outside standard calculus teachings and may require advanced techniques involving Legendre canonical forms. Resources like Wolfram Alpha are recommended for testing integral complexity.

PREREQUISITES
  • Understanding of elliptic integrals and functions
  • Familiarity with polynomial factorization techniques
  • Knowledge of substitution methods in integration
  • Experience with computational tools like Wolfram Alpha
NEXT STEPS
  • Research the properties and applications of elliptic integrals
  • Learn about Legendre canonical forms and their significance in integration
  • Explore advanced integration techniques not covered in standard calculus courses
  • Investigate resources for complex integral evaluation, such as specialized textbooks or online platforms
USEFUL FOR

Mathematicians, advanced calculus students, and anyone interested in the complexities of integrating non-standard functions, particularly those involving elliptic integrals.

askor
Messages
168
Reaction score
9
How do you integrate ##\frac{1}{\sqrt{x^3 + x^2 + x + 1}} \, dx##?

Please give me some hints and clues.

Thank you
 
Physics news on Phys.org
I would write the polynomial as ##(x^2+1)(x+1)## and try a suitable substitution like ##x^2+1=u## or similar.
 
  • Like
Likes   Reactions: pinball1970
Do you have specific bounds to integrate between? Wolfram alpha suggests the answer to this is you do not.
 
Elliptic integrals!
 
For
x^3+x^2+x+1 \ge 0
x \ge -1
You should take care of integral interval for finite and real result.
 
askor said:
How do you integrate ##\frac{1}{\sqrt{x^3 + x^2 + x + 1}} \, dx##?

Please give me some hints and clues.
It's a pretty interesting subject, elliptic integrals and functions if you're into that sort of thing. Check Wikipedia article: Elliptic integrals

. . . , with the appropriate reduction formula, every elliptic integral can be brought into a form that involves integrals over rational functions and the three Legendre canonical forms (i.e. the elliptic integrals of the first, second and third kind).

So it looks like you can express your integand as rational functions and the first, second, and third elliptical integrals and compute them using arithemetic-geometric means as per the reference. Sounds like an interesting research project but looks like it would take a bit of effort.
 
So, it's an advance integration that did not taught in standard Calculus textbook, am I right?

May I know what book that teach an integration like this?
 
What about this?

$$\int \frac{1}{\sqrt{x^3 + 6x^2 + 11x + 6}} \, dx$$

How do you integrate above?

Please give me a clues and hints.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
3K
Replies
5
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 30 ·
2
Replies
30
Views
1K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 31 ·
2
Replies
31
Views
4K