Definite Triple Integral to Series

Click For Summary

Homework Help Overview

The discussion revolves around evaluating the triple integral \(\int^{1}_{0}\int^{1}_{0}\int^{1}_{0}\frac{1}{1+x^2 y^2 z^2}\) and its relationship to the series \(\sum^{∞}_{n=0}\frac{1}{(2n+1)^3}\). Participants are exploring the connections between the integral and the series, questioning the validity of their equality.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss potential variable changes and the use of Jacobians, though initial attempts seem unfruitful. There is also mention of series expansions, particularly arcsin or arctan, as possibly relevant but uncertain how to apply them. Questions arise about the bounds of the integral and series, leading to considerations of their potential equality.

Discussion Status

Participants are actively engaging with the problem, noting upper and lower bounds for both sides of the equation. There is a recognition that the left-hand side (LHS) is less than or equal to 1, while the right-hand side (RHS) exceeds 1, suggesting they cannot be equal. However, no consensus has been reached on the overall evaluation of the integral or series.

Contextual Notes

Some participants express uncertainty about the necessary steps to evaluate the integral and how to incorporate series expansions. The discussion reflects a lack of complete information on the methods required for resolution.

Elysian
Messages
33
Reaction score
0

Homework Statement



Does the triple integral
\int^{1}_{0}\int^{1}_{0}\int^{1}_{0}\frac{1}{1+x^2 y^2 z^2} = \sum^{∞}_{n=0}\frac{1}{(2n+1)^3}

Homework Equations





The Attempt at a Solution


I've not a single clue on what to do with this problem. I figured maybe I could find a decent conversion of variables and find the Jacobian and switch variables to make this easier but tht didn't seem to work.

I don't know why but I think the series expansion of arcsin or arctan is needed here, but I'm not exactly sure how to incorporate it in. I don't even know how to evaluate this triple integral..
 
Physics news on Phys.org
Elysian said:

Homework Statement



Does the triple integral
\int^{1}_{0}\int^{1}_{0}\int^{1}_{0}\frac{1}{1+x^2 y^2 z^2} = \sum^{∞}_{n=0}\frac{1}{(2n+1)^3}


Hint: the integrand is ##\leq 1##, so does that give you an upper bound for the left hand side? Notice also that the first term of the series on the right hand side is ##1##, so that gives you a lower bound for the right hand side.
 
Last edited:
jbunniii said:
Hint: the integrand is ##\leq 1##, so does that give you an upper bound for the left hand side? Notice also that the first term of the series on the right hand side is ##1##, so that gives you a lower bound for the right hand side.

Ohh I think I get what you mean

The upper bound for the LHS is 1, and the first term of the right hand side is 1 and then adding constants, so they can't be equal?

There's only one intersection of their ranges so it doesn't work out then I guess?
 
Elysian said:
The upper bound for the LHS is 1, and the first term of the right hand side is 1 and then adding constants, so they can't be equal?
That's right, the LHS is ##\leq 1##, and the RHS is ##> 1##, so they can't be equal.
 

Similar threads

  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 105 ·
4
Replies
105
Views
10K
  • · Replies 19 ·
Replies
19
Views
3K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
4
Views
2K
Replies
2
Views
2K
Replies
10
Views
2K
Replies
3
Views
2K