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

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In summary, the limit of frac(x)/x as x tends to infinity is 0. This can be proven using the squeeze theorem since frac(x) always lies between 0 and 1, and the denominator is an increasing function that tends to infinity. This contradicts with WolframAlpha's answer of 0, which would only be true if frac(x) is always equal to 0. Therefore, the limit is undefined.
  • #1
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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  • #2
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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  • #3
Thank you Titan97 for clearing that up. So the limits would be 0 this time.
 
  • #4
You can use the squeeze theorem here since ##0 \le \text{frac(x)} < 1##.
 
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  • #5
SataSata said:
Thank you Titan97 for clearing that up. So the limits would be 0 this time.
Yes.
 
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Related to Limits of frac(x)/x: Is WolframAlpha Wrong?

1. What is the concept of "limits" in mathematics?

Limits in mathematics refer to the behavior of a function as its inputs approach a certain value. It helps determine the value that a function approaches, or "approaches" but never reaches, as its input gets closer and closer to a particular value.

2. How is the limit of frac(x)/x calculated?

The limit of frac(x)/x is calculated by evaluating the function at a specific value and then finding the limit as the input approaches that value. In this case, the limit of frac(x)/x as x approaches 0 would be calculated by plugging in values closer and closer to 0 (such as 0.1, 0.01, 0.001, etc.) and observing the resulting output.

3. Why is WolframAlpha showing a different result for the limit of frac(x)/x?

WolframAlpha uses a complex algorithm to calculate limits, which may differ from other methods used to calculate limits. Additionally, the result shown may be an approximation rather than an exact value.

4. Can the limit of frac(x)/x be proven to be wrong?

No, the limit of frac(x)/x is a well-established mathematical concept and cannot be proven to be wrong. However, it is always important to check the calculations and assumptions used to determine the limit.

5. What are the practical applications of understanding the limits of a function?

Understanding the limits of a function is important in many areas of mathematics, such as calculus, where it is used to solve problems related to rates of change and optimization. It also has practical applications in fields such as physics, engineering, and economics.

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