Integral - Algebraic Manipulation?

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Homework Help Overview

The discussion revolves around the integral of the function \(\int \frac{x}{x+d}dx\), focusing on algebraic manipulation techniques for integration.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore various algebraic manipulations, including rewriting the integrand and considering polynomial long division. Questions arise about intuitive methods for recognizing simplifications.

Discussion Status

Participants have shared different approaches to simplifying the integral, with some suggesting straightforward algebraic techniques. There is an acknowledgment of varying levels of intuition regarding these methods, but no consensus has been reached on a single preferred approach.

Contextual Notes

Some participants express uncertainty about the best method to simplify the integrand, indicating a need for clearer strategies in algebraic manipulation.

Prologue
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Homework Statement



[tex]\int \frac{x}{x+d}dx[/tex]

The Attempt at a Solution



I tried parts and that turned out horribly so I fired up maple. First move it makes is 'Rewrite Rule'. I've never heard of a rewrite rule but I supposed it could be some algebraic massaging. I ended up looking at it this way:

[tex]\frac{x}{x+d} = 1-1+\frac{x}{x+d} = \frac{x+d}{x+d}-\frac{x+d}{x+d}+\frac{x}{x+d} = \frac{x+d}{x+d}+\frac{x-d-x}{x+d} = 1-\frac{d}{x+d}[/tex]

Which then is easily integrable. My question is, is there a snappier way to think of this/do it?
 
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Just divide x by x+d and you'll get the term on the rightmost of your equalities.
 
As in polynomial long division?

edit: Or is there some way that is easy to see what will happen? Basically it isn't straight up intuitive for me to realize that x/x+d is 1-d/x+d, I'm trying to find a quick method to deal with it.
 
Last edited:
[tex]\int\frac{x+d-d}{x+d}dx[/tex]

Break it and integrate.
 
That's much shorter than what I did, thanks.
 

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