Partial Fractions: Deciding Formula Without Memorization

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Discussion Overview

The discussion revolves around the topic of partial fractions, specifically how to determine the appropriate formula to use without relying on memorization. Participants explore the theory and application of partial fraction decomposition in mathematical contexts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses difficulty in remembering the different partial fraction formulas and seeks a method to decide which to use based on the expression itself.
  • Another participant questions the context of using partial fractions, suggesting that the process typically involves splitting the fraction after factoring the denominator.
  • A participant outlines that over the reals, prime polynomials are either linear or quadratic, and discusses the structure of numerators based on the degree of the denominator's factors.
  • Further elaboration is provided on the decomposition of a specific expression, detailing the necessary components and constants involved in the partial fraction setup.
  • There is a playful exchange regarding whether the process of partial fractions is straightforward, with one participant asserting it is simple, while another contests this view.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the process of partial fractions is straightforward. There are competing views on the complexity of the topic, with some asserting simplicity and others suggesting it is more complex.

Contextual Notes

Participants discuss the conditions under which certain formulas apply, including the nature of prime polynomials and the structure of numerators, but do not resolve the broader implications or nuances of partial fraction decomposition.

Who May Find This Useful

This discussion may be useful for students and practitioners in mathematics who are exploring the concept of partial fractions and looking for insights on how to approach the topic without memorization.

pivoxa15
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I have never remebered the different partial fraction forumlas. Is there a way to decide which partial fraction formula to use just by looking at the expression?
 
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Partial fraction formulae?

I thought you just did partial fractions... what's the context? Normally you just split the fraction after factoring the denominator into a sum of fractions with denominators equal to the different factored parts
 
over R, the only prime polynomials are linear or quadratic. the numerators are either constant or linear respectively.

if f^n is a factor of the denominator, where f is prime, we need to allow for all fractions whose greatest common denom is f^r, so we have

to allow a/f , b/f^2, c/f^3, ..., d/f^n, for appropriate numerators.

e.g. to decom,pose h/[x^2(x^2+x+1)^3] we set it equal to

a/x + b/x^2 + (cx+d)/(x^2+x+1) +(ex+f)/(x^2+x+1)^2 + (gx+h)/(x^2+x+1)^3.where a,b,c,d,e,f,g,h, are constants.
 
Last edited:
mathwonk said:
over R, the only prime polynomials are linear or quadratic. the numerators are either constant or linear respectively.

if f^n is a factor of the denominator, where f is prime, we need to allow for all fractions whose greatest common denom is f^r, so we have

to allow a/f , b/f^2, c/f^3, ..., d/f^n, for appropriate numerators.

e.g. to decom,pose h/[x^2(x^2+x+1)^3] we set it equal to

a/x + b/x^2 + (cx+d)/(x^2+x+1) +(ex+f)/(x^2+x+1)^2 + (gx+h)/(x^2+x+1)^3.


where a,b,c,d,e,f,g,h, are constants.

Is that all there is to partial fractions? It isn't as mystifying as it appears.
 
pivoxa15 said:
Is that all there is to partial fractions?
Yes it is! :smile:
It isn't as mystifying as it appears.
No, it isn't! :smile:
 

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