Limit of sequence equal to limit of function

In summary, the conversation revolves around the theorem that states if the limit of a function g(e) is L when e approaches a positive value, and the sequence {a_n} approaches a from the right but never equals a, then the sequence {g(a_n)} approaches L as n approaches infinity. The participants discuss its application to the situation where we have two limits, L_1 and L_2, and question whether L_1 equals L_2. The conversation then provides evidence for the theorem by stating the facts that g(e) is a function that approaches L as e approaches 0, and the sequence {1/n} approaches 0 from the right.
  • #1
Castilla
241
0
Suppose

lim (when n -> oo) of sup {f(x) / x belongs to (0, 1/n) } = L_1, and


lim (when e -> 0+) of sup {f(x) / x belongs to (0, e) } = L_2.


(e is simply epsilon).

It seems pretty obvious, but it is truth that L_1 = L_2 ?

Thanks for your help.
 
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  • #2
Maybe this theorem works.

If:
1. Lim g(e) = L ( when e -> a+ )
2. The sequence {a_n} -> "a"+ (but there is not a_n = a),

Then the sequence { g(a_n) } -> L (when n -> oo).

So in the case I stated previously I have these facts:

1. Let "g" be the function / g(e) = sup { f(x) / x belongs to (0,e) }
2. Lim g(e) = L ( when e -> 0+ ).
3. The sequence {1/n} -> 0+

So by the theorem I got { g(1/n) } -> L (when n -> oo), or in other words
sup { f(x) / x belongs to (0,1/n) } -> L (when n -> oo).

Now I would thank if someone can bless this.
 
  • #3


Yes, it is true that L_1 = L_2. This is because as n approaches infinity, the interval (0, 1/n) becomes smaller and smaller, and as e approaches 0, the interval (0, e) also becomes smaller and smaller. This means that the limit of the sequence and the limit of the function are being evaluated at the same point, which is essentially the same concept. Therefore, the limit of the sequence must equal the limit of the function, resulting in L_1 = L_2. This is a fundamental property of limits and is often used in calculus and analysis to prove the convergence of sequences and functions.
 

1. What is the definition of a limit of a sequence equal to the limit of a function?

The limit of a sequence is the value that the terms of the sequence approach as the index of the sequence approaches infinity. The limit of a function is the value that the function approaches as the independent variable approaches a specific value. In other words, the limit of a sequence and the limit of a function both describe the behavior of a mathematical object as it approaches a specific value or infinity.

2. How is the limit of a sequence related to the limit of a function?

The limit of a sequence can be thought of as a special case of the limit of a function, where the independent variable is the index of the sequence. In other words, the limit of a sequence is the limit of a function with a discrete domain instead of a continuous domain.

3. Can the limit of a sequence be equal to the limit of a function for all functions and sequences?

No, the limit of a sequence can only be equal to the limit of a function if the function and sequence have the same limit. This is not always the case, as some functions may not have a limit or may have a different limit than the sequence that is being compared to.

4. How can we use the limit of a sequence equal to the limit of a function in real-world applications?

In real-world applications, the concept of the limit of a sequence equal to the limit of a function is often used to model and predict the behavior of systems or processes that approach a specific value or infinity. This can be seen in fields such as physics, economics, and engineering.

5. What are some common misconceptions about the limit of a sequence equal to the limit of a function?

One common misconception is that the limit of a sequence and the limit of a function must always be equal. As mentioned before, this is not always the case and depends on the specific function and sequence being compared. Another misconception is that the limit of a sequence must always exist for the limit of a function to exist, which is not necessarily true as some functions may have a limit even if the sequence does not converge.

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