Is it possible to find the integral of ##f(x)/x^2##?

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Discussion Overview

The discussion revolves around the possibility of integrating the expression ##f(x)/x^2##, where ##f(x)## is an unspecified function. Participants explore the conditions under which such an integral might be feasible, considering various types of functions and their domains.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant expresses uncertainty about the integrability of ##f(x)/x^2##, noting that Wolfram Alpha cannot provide a solution, but questions its reliability.
  • Another participant emphasizes the need for more information about ##f(x)## and its domain, stating that some functions may not be integrable.
  • A claim is made that for arbitrary ##f(x)##, the integral cannot be computed without knowing the specific form of ##f(x)##.
  • It is suggested that integration by parts could be used to express the integral in terms of other integrals or derivatives of ##f(x)##, but this depends on the nature of ##f(x)##.
  • Participants discuss the implications of defining ##f(x)## over a domain that includes all integers, with some arguing that this does not necessarily affect integrability.
  • A participant proposes that if there were a straightforward method to integrate ##f(x)/x^2##, one could define a new function ##g(x)=x^2 f(x)## and compute the integral of ##g(x)/x^2## instead.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the integrability of ##f(x)/x^2##. Multiple competing views remain regarding the conditions under which the integral can be computed, and the discussion highlights differing perspectives on the necessity of knowing the specific form of ##f(x)##.

Contextual Notes

The discussion reflects limitations in the assumptions about ##f(x)##, particularly regarding its form and domain, which are critical for determining integrability. There are unresolved mathematical steps related to the integration technique being developed.

MevsEinstein
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TL;DR
What the title says
I am creating an integration technique and I have only one step left! I need to integrate ##f(x)/x^2## and then I'll be done. So I want to know if integrating this is possible.

Wolfram Alpha can't integrate it, but there are problems that it couldn't solve, so I'm not 100% sure that Wolfram Alpha is right.
 
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You'll need to tell us about f(x) and the domain. Some functions just aren't integrable. For example, if ##f(x)=x##, ##\int_{-1}^1 \frac{1}{x} \, dx## doesn't work. Wolfram Alpha told me so.
 
For arbitrary f(x), the answer is no.
 
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You can't get an explicit solution without knowing what f(x) is. You can use integration by parts to express the integral in terms of integrals or derivatives of f(x). For some f(x) this can lead to simpler expressions, but that depends on f(x).
 
MevsEinstein said:
So what if ##f(x)## has a domain that accepts all integers?
That does not narrow things down very much.

If you have a function that is integrable and you undefine it at all integers, it does not become unintegrable.
 
MevsEinstein said:
So what if ##f(x)## has a domain that accepts all integers?
That doesn't help because:

DaveE said:
You'll need to tell us about f(x)
mathman said:
For arbitrary f(x), the answer is no.
mfb said:
You can't get an explicit solution without knowing what f(x) is.

Not sure how many different ways we can say the same thing.
 
MevsEinstein said:
So what if ##f(x)## has a domain that accepts all integers?
What do you mean? Didn't @DaveE provide you with an example of an ##f(x)## that is defined for all ##\mathbb{R}##?
 
If there was an easy way to integrate ##f(x)/x^2##, then given ##f##, you can just say ##g(x)=x^2 f(x)## and then compute the integral of ##g(x)/x^2##. Then you have the integral of ##f##.

So whatever other intermediate steps you were going to make, they wouldn't actually be needed.
 
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