Yet another proof function continuity related

In summary, the conversation is about approaching a question with the help of tips and hints. The key idea is to use the continuity of f at L and the limit of g at a to find positive real numbers d and c that satisfy the given conditions.
  • #1
bluevires
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http://www.uAlberta.ca/~blu2/question1.gif


hey guys, I've tried this question and here's what I come up with, however I don't think this is anywhere near the right answer, but it does show the direction that I'm trying to work toward, I would appreciate any tips/help on how should I approach this question.

http://www.uAlberta.ca/~blu2/answer.gif
 
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  • #2
Let e be an arbitrary positive real number. Since f is continuous at L, there is a positive real d such that |L-x|< d implies |f(L)-f(x)| < e. Since the limit of g at a is L, then there exists a positive real c such that |x-a| < c implies |g(x)-L| < d. Is this enought of a hint?
 
  • #3


I understand your approach and appreciate your effort in trying to solve this problem. However, I believe there may be some misunderstandings about the concept of continuity and how to prove it. Continuity is a fundamental concept in mathematics and is closely related to the concept of limits. In order to prove that a function f(x) is continuous at a point x=a, we need to show that the limit of f(x) as x approaches a is equal to the value of f(a). In other words, f(x) must be defined and have a unique value at x=a, and the limit of f(x) as x approaches a must exist and be equal to f(a).

Looking at the provided graph, we can see that the function is defined and has a unique value at x=1, which is f(1)=2. However, in order to prove continuity, we also need to show that the limit of f(x) as x approaches 1 exists and is equal to 2.

To do this, we can use the definition of a limit and show that for any given epsilon (ε), we can find a corresponding delta (δ) such that for all x within δ of 1, the difference between f(x) and 2 (the value of the limit) is less than epsilon. This would prove that the limit of f(x) as x approaches 1 is indeed 2, and therefore the function is continuous at x=1.

In summary, proving continuity involves showing that a function is defined and has a unique value at a point, and that the limit of the function at that point exists and is equal to the value of the function. I suggest revisiting the definition of continuity and limits, and using that as a guide to approach this question. Keep up the good work!
 

FAQ: Yet another proof function continuity related

What is a proof function and how is it related to continuity?

A proof function is a mathematical function used to prove the continuity of another function. It involves using the definition of continuity to show that the given function is continuous at a specific point, or over a given interval. By using a proof function, we can demonstrate that a function has no abrupt changes or discontinuities, and therefore can be considered continuous.

How do you know when a function is continuous?

A function is considered continuous when there are no abrupt changes or "jumps" in its graph. This means that the function is defined and has a limit at every point on its domain. Another way to test for continuity is to see if the value of the function at a specific point is the same as the limit of the function at that point. If these two values are equal, the function is continuous.

Can a function be continuous at some points and not at others?

Yes, a function can be continuous at some points and not at others. For example, a function may be continuous on a closed interval, but not continuous at the endpoints of that interval. This is because the definition of continuity requires that the limit of the function exists at every point within the domain, including the endpoints.

What is the difference between pointwise continuity and uniform continuity?

Pointwise continuity refers to the continuity of a function at individual points. It means that the limit of the function exists at each point within the domain. On the other hand, uniform continuity refers to the continuity of a function over an entire interval. It means that the function is continuous at every point within the interval, and the rate of change of the function is consistent over the entire interval.

How do you prove the continuity of a function using the epsilon-delta definition?

To prove the continuity of a function using the epsilon-delta definition, you must show that for any given epsilon (ε), there exists a corresponding delta (δ) such that if the distance between the input and a specific point is less than delta, then the distance between the output and the limit is less than epsilon. In other words, as the input gets closer to a specific point, the output gets closer to the limit. If this condition is met, the function is considered continuous at that point.

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