Explain why this is no good as a definition of continuity

In summary, continuity is a mathematical concept that describes a function with no sudden jumps or gaps, where the input and output values get closer as the input values get closer. However, this definition is considered "no good" because it is not specific enough and does not clearly explain the criteria for continuity. The formal definition of continuity uses limits and specific criteria for the function to be continuous. An example of a function that meets the first definition but not the formal definition is a function with a removable discontinuity. To improve this definition, specific criteria and more intuitive explanations of continuity can be included.
  • #1
gregy6196
13
0
Explain why this is no good as a definition of continuity at a point a (either by giving an example of a continuous function that does not satisfy the definition or a discontinuous one that does):
Given ε > 0 there exists a [itex]\delta[/itex] > 0 such that |x – a| < [itex]\epsilon[/itex] [itex]\Rightarrow[/itex] |f(x) – f(a)| < [itex]\delta[/itex]
 
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  • #2


There will always exist δ. For example f(x)=0 for x< 0 and f(x) = 1 otherwise. Then your definition will have continuity at 0 using δ > 1.
 

Related to Explain why this is no good as a definition of continuity

1. What is the definition of continuity?

The definition of continuity is a mathematical concept that describes a function that has no sudden jumps or gaps. It means that, as the input values of a function get closer and closer, the output values also get closer and closer.

2. Why is this definition considered "no good"?

This definition is considered "no good" because it is not specific enough. It does not clearly explain what "sudden jumps or gaps" mean and how close the input and output values need to be to be considered continuous.

3. How does this definition differ from the formal definition of continuity?

The formal definition of continuity is a mathematical statement that uses limits to describe the behavior of a function at a specific point. It also includes specific criteria for the function to be considered continuous, such as the limit of the function at the point being equal to the function value at that point.

4. Can you provide an example of a function that meets this definition but does not meet the formal definition of continuity?

Yes, a function that has a removable discontinuity (a hole) at a specific point would meet this definition but not the formal definition of continuity. For example, the function f(x) = (x^2 - 1)/(x - 1) has a removable discontinuity at x = 1, as the limit of the function at x = 1 is 2, but the function value at x = 1 is undefined.

5. How can this definition be improved?

This definition can be improved by specifying the criteria for a function to be considered continuous, such as the limit of the function at a point being equal to the function value at that point. It can also explain the concept of continuity in more intuitive terms, such as a function that can be drawn without lifting the pen from the paper.

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