Integration of an infinite product

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Discussion Overview

The discussion revolves around the integration of an infinite product, specifically focusing on the integral of a product of polynomial expressions. Participants explore methods for integration, including integration by parts, and seek to derive a general formula for the coefficients of the resulting polynomial after expansion.

Discussion Character

  • Exploratory
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant expresses difficulty in integrating an infinite product and suggests integration by parts, noting that it becomes complex.
  • Another participant questions whether the integral in question is indeed of an infinite product, specifically asking about the expression ##\int \prod_{m=1}^\infty (x^2 + m) \, dx##.
  • A participant provides an example of a finite product and its expansion, detailing the polynomial formed and the coefficients involved.
  • Another participant emphasizes the need to derive a general formula for the coefficients in the polynomial expansion, suggesting a summation approach for multiple indices.
  • One participant requests further clarification on a previous response, indicating some uncertainty about the proposed ideas.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus, as there are differing interpretations of the problem and various approaches suggested without agreement on a definitive method or solution.

Contextual Notes

The discussion includes assumptions about the nature of the infinite product and the integration process, which remain unresolved. The dependence on specific definitions and the complexity of deriving a general formula for coefficients are also noted as limitations.

ecpietscheck
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Hey guys, what sup
I need you all to help me in resolving the integral of an infinite product...
i was thinking of perhaps integrating by parts, but when yo do that the integration becomes brutally expansive...
any ideas?
thank you all very much

the variable which is aimed to be integrated is x btw...
 

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You wrote down a finite product. Do you in fact want ##\int \prod_{m=1}^\infty (x^2 + m) \, dx##?
 
for example

(x*x+1)*(x*x+2)*(x*x+3)*(x*x+4) = x^8 + a*x^6 + b*x^4 + c*x^2 + 1*2*3*4

1*2*3*4 = 4!


(x*x+1)*(x*x+2)*(x*x+3)*(x*x+4) = x^8 + 10x^6 + 35x^4 + 50x^2 + 24

Each member must be integrated.

∫ x^8 + 10x^6 + 35x^4 + 50x^2 + 24 dx =

= x^9/9 + 10x^7/7 + 7x^5 +50x^3/3 +24x + C

kamke
 
kamke said:
(x*x+1)*(x*x+2)*(x*x+3)*(x*x+4) = x^8 + 10x^6 + 35x^4 + 50x^2 + 24

Each member must be integrated.
The problem is to get a general formula for those coefficients.

Basically ##\displaystyle \sum_{i,j,...=1, i<j<...}^n i*j*k*...## with 0 to n indices in the sum.
The second sum, for example, sums 1*2+1*3*...+1*n + 2*3+2*4+...+2*n+...
 
MFB, that answer seems a bit unclear
perhaps any other ideas?
 

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