Limits of frac(x)/x: Is WolframAlpha Wrong?

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Discussion Overview

The discussion revolves around the limit of the function $$\frac{frac(x)}{x}$$ as $$x$$ approaches infinity, where $$frac(x)$$ is defined as $$x$$ minus the floor function of $$x$$. Participants explore the implications of this limit, the application of the squeeze theorem, and the correctness of WolframAlpha's output.

Discussion Character

  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant suggests that since $$frac(x)$$ is always between -1 and 1, the limit could be considered undefined, questioning WolframAlpha's assertion that the limit is 0.
  • Another participant clarifies that $$frac(x)$$ is always positive and lies between 0 and 1, indicating that the limit should indeed approach 0 as $$x$$ approaches infinity.
  • Several participants agree on the application of the squeeze theorem, stating that since $$0 \leq frac(x) < 1$$, the limit of $$\frac{frac(x)}{x}$$ should be 0.

Areas of Agreement / Disagreement

There is a mix of viewpoints, with some participants questioning the limit's definition and others supporting the conclusion that the limit is 0. The discussion reflects uncertainty regarding the interpretation of the limit and the correctness of WolframAlpha's output.

Contextual Notes

Participants have not fully resolved the implications of the limit's behavior as $$x$$ approaches infinity, particularly regarding the conditions under which the limit is defined.

SataSata
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$$\lim_{x\to\infty} \frac {frac(x)} {x} $$
frac(x) is x minus floor function of x. So if x = 2.5, floor function = 2 and frac(x) = 0.5
Hence frac(x) will always be a number between -1 and 1 but never -1 and 1.

By squeeze theorem,
-1 < frac(x) < 1
-1/x < frac(x)/x < 1/x
0 < frac(x)/x < 0

Does this means that $$\lim_{x\to\infty} \frac {frac(x)} {x} = Undefined? $$
Since it is between 0 but not 0.
However WolframAlpha gives the answer as 0.
Shouldn't it be 0 only if it is $$0 \leqslant frac(x)/x \leqslant 0$$
So did I do something wrong or is WolframAlpha wrong?
 
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SataSata said:
frac(x) is x minus floor function of x. So if x = 2.5, floor function = 2 and frac(x) = 0.5
No. frac{x} is always positive and lies between 0 and 1.

In the limit, the numerator always lies between 0 and 1 while the denominator is an increasing function that tends to infinity when x tends to infinity.

So what will be ##\lim_{x\to\infty}\frac{frac(x)}{x}##
 
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Thank you Titan97 for clearing that up. So the limits would be 0 this time.
 
You can use the squeeze theorem here since ##0 \le \text{frac(x)} < 1##.
 
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SataSata said:
Thank you Titan97 for clearing that up. So the limits would be 0 this time.
Yes.
 
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