How does this second integral equal +infinity instead of -infinity?

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The discussion revolves around the evaluation of limits related to a mathematical expression, specifically questioning the behavior of a second limit as it approaches infinity. Participants are examining the divergence of these limits and their implications in the context of calculus.

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  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are exploring the reasoning behind the divergence of the second limit, with some suggesting that it should diverge to +∞ instead of -∞. There is a focus on the behavior of the variable b as it approaches 1 from above, and how this affects the limit's outcome.

Discussion Status

There is an ongoing exploration of the limits involved, with some participants providing insights into the significance of the signs in the limits. Clarifications about the nature of the expressions being limits rather than integrals have been introduced, indicating a shift in understanding.

Contextual Notes

Participants are navigating potential misunderstandings regarding the definitions of the mathematical expressions in question, particularly the distinction between limits and integrals. The discussion also highlights the importance of the approach of variables towards specific values in limit evaluation.

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1. ...How does this 2nd integral diverge to +∞? It seems to me that it would diverge to -∞... :/

lim (\frac{-1}{a - 1} - \frac{-1}{0 - 1}) + lim (\frac{-1}{2 - 1} - \frac{-1}{b - 1}) + lim (\frac{-1}{c - 1} - \frac{-1}{2 - 1})
a→1- b→1+ c→∞

2. First integral: -1/(tiny negative #) - 1 = +∞

Second integral: -1 + 1/(tiny negative #) = -1 + -∞ = -∞ <----This answer is supposed to be +∞. How?!

Third Integral: -1/(∞ - 1) + 1 = 0 + 1 = 0

The only thing I don't get it the second integral! :(
Help please!
Thanks! :)
 
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Lo.Lee.Ta. said:
1. ...How does this 2nd integral diverge to +∞? It seems to me that it would diverge to -∞... :/

lim (\frac{-1}{a - 1} - \frac{-1}{0 - 1} + lim (\frac{-1}{2 - 1} - \frac{-1}{b-1}
a→1- b→1+
+ lim (\frac{-1}{c - 1} - \frac{-1}{2 - 1}
c→∞


2. First integral: -1/(tiny negative #) - 1 = +∞

Second integral: -1 + 1/(tiny negative #) = -1 + -∞ = -∞ <----This answer is supposed to be +∞. How?!
It is NOT "tiny negative". -\frac{-1}{b- 1}= \frac{1}{b- 1} and b is approaching 1 from above so b> 1 and b- 1> 0.

Third Integral: -1/(∞ - 1) + 1 = 0 + 1 = 0

The only thing I don't get it the second integral! :(
Help please!
Thanks! :)
 
If b is approaching 1 from the right, it seems like it would be very close to the number 1.

Maybe it would be 1.00000000001

So 1/(1.00000000001 + 1) = 1/.00000000001 = +∞

I usually pay no attention to the - or + in the limit, but I see it's important! O_O
Thanks!
 
These are not integrals: they are limits.
 

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