Integration on a open interval?

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Homework Help Overview

The original poster is inquiring about the process of integrating a function over an open interval, specifically the function f(x) = x^2 + 2x + 3 on the interval (2, 7). They emphasize the distinction between open and closed intervals and seek clarification on how this affects integration.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Some participants question the significance of integrating over an open interval versus a closed interval, suggesting that the contribution from the endpoints may be negligible. Others raise concerns about functions whose antiderivatives might behave differently at the endpoints, particularly in relation to limits.

Discussion Status

The discussion is exploring various interpretations of the implications of open intervals in integration. Some participants have offered insights regarding the negligible contribution from endpoints, while others are probing deeper into specific cases that might challenge this notion, such as distributions with singularities.

Contextual Notes

There is an ongoing examination of the assumptions surrounding the behavior of functions and their antiderivatives at the boundaries of open intervals, particularly in relation to different types of functions and potential singularities.

GreenPrint
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Homework Statement



I was wondering how one integrates on a open interval. For example let's say I wanted to integrate the function f(x) = x^2 + 2x + 3 on (2,7). Note that it's on the OPEN INTERVAL not closed of all the x values from 2 to 7 not including 2 to 7. I'm not trying to integrate on [2,7] but on (2,7). How do I do this? Thanks. Any ideas or suggestions or anything at all would be appreciated.

Homework Equations





The Attempt at a Solution

 
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It doesn't make any difference. Why do you think it does? The contribution from the endpoints is zero.
 
I know it may not make a difference for this function but what about functions whose anti derivatives are different if you were to take the left hand limit of the anti derivative and the right hand limit of the derivative at the points that were to determine the open interval
 
GreenPrint said:
I know it may not make a difference for this function but what about functions whose anti derivatives are different if you were to take the left hand limit of the anti derivative and the right hand limit of the derivative at the points that were to determine the open interval

The only way the contribution from a single point can make a difference is if you are integrating distributions with singularities. Like delta functions. Distributions are different from functions. Are you integrating distributions?
 

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