Formal Proof of Uniform Continuity on a Closed Interval

In summary: Also, "the minimum of delta_1 and delta_2 is the delta we want for [a,c]" is not a complete sentence. Just write out the full sentence: "The minimum of delta_1 and delta_2, denoted as delta_3, is the delta we want for [a,c]."
  • #1
MathSquareRoo
26
0

Homework Statement



Prove that if f is uniformly continuous on [a,b] and on [a,c] implies that f is uniformly continuous on [a,c].

Homework Equations




The Attempt at a Solution



This is my rough idea for a proof, can someone help be say this more formally? Is my thinking even correct?

Let epsilon > 0.
Then there is some delta_1 for [a,b] and some delta_2 for [b,c].
Then the minimum of delta_1 and delta_2 is the delta we want for [a,c].
 
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  • #2
MathSquareRoo said:

Homework Statement



Prove that if f is uniformly continuous on [a,b] and on [a,c] implies that f is uniformly continuous on [a,c].

Homework Equations




The Attempt at a Solution



This is my rough idea for a proof, can someone help be say this more formally? Is my thinking even correct?

Let epsilon > 0.
Then there is some delta_1 for [a,b] and some delta_2 for [b,c].
Then the minimum of delta_1 and delta_2 is the delta we want for [a,c].

Sure, that's the idea. It's not that hard to fill that out to a formal proof.
 
  • #3
Thanks. What changes should I make to make it more formal?
 
  • #4
MathSquareRoo said:
Thanks. What changes should I make to make it more formal?

Just fill in some words. "there is some delta_1 for [a,b]" doesn't mean much. There is some delta_1 for [a,b] such that what? I know what you mean, but spell it out.
 

1. What is continuity in real analysis?

Continuity in real analysis refers to a mathematical property of a function where there are no abrupt changes or discontinuities in its graph. This means that the function is smooth and can be drawn without lifting the pen from the paper.

2. How is continuity different from differentiability?

While both continuity and differentiability are properties of functions, they are distinct concepts. Continuity focuses on the behavior of a function at a point, while differentiability looks at how the function changes between points. A function can be continuous but not differentiable, but it cannot be differentiable without being continuous.

3. What is the importance of continuity in real analysis?

Continuity is crucial in real analysis as it allows us to study the behavior of functions in a smooth and predictable manner. It enables us to analyze functions and their derivatives, which are essential in many mathematical applications, such as optimization, physics, and engineering.

4. How can we determine if a function is continuous?

A function is continuous at a point if the limit of the function at that point exists and is equal to the value of the function at that point. To determine if a function is continuous on an interval, we need to check the continuity at each point in the interval.

5. Can a function be discontinuous at a single point?

Yes, a function can be discontinuous at a single point. This occurs when the limit of the function at that point does not exist or is not equal to the value of the function at that point. This is known as a point discontinuity or a removable discontinuity.

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