How Can You Integrate x/(a^2+x^2)^(3/2) Without Explicit Substitution?

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Discussion Overview

The discussion revolves around the integration of the function x/(a^2+x^2)^(3/2) without using explicit substitution. Participants explore the methods and reasoning behind a professor's approach as presented in a video, questioning the validity and steps taken in the integration process.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant notes that the professor integrated x/(a^2+x^2)^(3/2) as if it were 1/(a^2+x^2)^(3/2), raising questions about how this is possible.
  • Another participant requests more information about the professor's method to clarify the integration process.
  • A participant describes the professor's integration step involving differentiation of the denominator and multiplication by the derivative of x^2, expressing confusion about the reasoning.
  • Some participants suggest examining the integrand more closely, proposing that it can be rewritten as a product rather than a quotient, hinting at a potential simplification.
  • There is a correction regarding the powers in the original question, indicating a misunderstanding that was addressed by a participant.
  • One participant concludes that the professor's method effectively used a substitution (u = x^2 + a^2) without explicitly stating it, suggesting a hidden substitution approach.

Areas of Agreement / Disagreement

Participants express differing views on the integration method used by the professor, with some supporting the idea of implicit substitution while others question the clarity and correctness of the approach. No consensus is reached regarding the validity of the integration technique.

Contextual Notes

Some participants note that the video link requires a login, limiting access to the original content being discussed. There is also mention of a potential mistake in the powers of the integrand, which may affect the understanding of the integration process.

abdo799
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in this video , the prof had to integrate x/(a^2+x^2)^3/2 , i know we usually do this using substitution , but in the video...he ignored the x and integrate like it was 1/(a^2+x^2)^3/2, how does that work?
 
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You will probably need to give more information about what he did.
 
he said integration of x/(a^2+x^2)^3/2= x*(-2)/(a^2+x^2)^1/2*2x
i really don't know what he did, he differentiated the bottom part then divided by new power and multiplied by differentiation of x^2
 
there was a mistake with the powers in the question and i corrected it
 
Look carefully at the integrand x/(a^2+x^2)^(2/3). What is the derivative of (a^2+x^2)? Is it x times some constant perhaps? Can you rewrite the integrand as the product of two expressions, rather than the quotient?

BTW, your video requires a login to view, so we can't see it.
 
SteamKing said:
Look carefully at the integrand x/(a^2+x^2)^(2/3). What is the derivative of (a^2+x^2)? Is it x times some constant perhaps? Can you rewrite the integrand as the product of two expressions, rather than the quotient?

BTW, your video requires a login to view, so we can't see it.


the power on the brakets is 3/2
 

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abdo799 said:
the power on the brakets is 3/2

The power on the brackets is immaterial. The principle remains.
 
SteamKing said:
The power on the brackets is immaterial. The principle remains.

i figured out what he did, he differentiated the bottom part...and that's it
 
  • #10
In other words he did exactly the "[itex]u= x^2+ a^2[/itex]" substitution, just not writing it out explicitly.
 

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