Limit of quotient of two functions

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Discussion Overview

The discussion revolves around the implications of the limit of the quotient of two functions, specifically whether the limit of f(x)/g(x) equaling 1 implies that the limits of f(x) and g(x) are equal. The scope includes mathematical reasoning and exploration of limit properties.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant suggests that if the limit of f(x)/g(x) equals 1, then it follows that the limits of f(x) and g(x) must also be equal.
  • Another participant counters that this implication does not necessarily hold, as the limits of f(x) and g(x) might not exist at the point in question.
  • A third participant agrees that if the individual limits exist, then they will be equal, but emphasizes that the existence of the limit of the quotient does not guarantee the existence of the limits of f and g.
  • One participant provides an example involving the limit of sin(x)/x as x approaches 1, questioning the clarity of the earlier statements.
  • A subsequent reply corrects the example to refer to the limit as x approaches 0 instead of 1.
  • A participant retracts their earlier statement, indicating a change in their position.

Areas of Agreement / Disagreement

Participants express disagreement regarding the implications of the limit of the quotient, with some asserting that the limits must be equal under certain conditions, while others maintain that the existence of the limits is not guaranteed.

Contextual Notes

Limitations include the potential non-existence of individual limits and the specific conditions under which the limits of f and g may be considered equal.

ModernLove
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Let f(x) and g(x) be functions.

Then if limit of f(x)/g(x) = 1. That implies lim f(x) = lim g(x) right?

Consider this proof.

lim f(x)/g(x) = 1
lim f(x) x lim 1/g(x) = 1
lim f(x) = 1 / (lim 1/g(x))
lim f(x) = lim g(x).
 
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No, the implication doesn't follow since the limits of f and g might not exist in the first place at the point where the limit of the quotient is 1.
 
Provided that the indivual limits actually exist then yes they will be equal. But just because the limit of f/g exists it doesn't mean that the limits of f and g neccessarily exist.


EDIT : No I'm not turning into a parrot, I must have posted the same time as arildno. :)
 
Last edited:
That's mind-reading, not parroting, uart.
 
arildno said:
That's mind-reading, not parroting, uart.

Or in this case just stating the obvious I think. :)
 
[tex]\lim_{x\rightarrow 1} \frac{\sin x}{x} = 1[/tex]

[tex]\lim_{x\rightarrow 1} \sin x \neq 1[/tex]

Can a mathematician clarify?
 
Eeh, you've got:
[tex]\lim_{x\to0}\frac{\sin(x)}{x}=1[/tex]
 
Doh! I retract my previous statement.
 

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