Proving Uniform Continuity of f+g with Triangle Inequality

In summary, the question posed is whether f + g is uniformly continuous in section I if g and f are also uniformly continuous in section I. The individual was able to prove this using the Triangle Inequality, but wondered if the same proof would hold for f-g. The expert suggests that the proof should still work with minor modifications, or alternatively, if it has been proven that f+g is uniformly continuous, then it can be shown that -g is also uniformly continuous and the same proof can be applied to show that f-g is uniformly continuous. The expert also welcomes the individual to the community.
  • #1
sergey_le
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Homework Statement
I didn't understand what I was supposed to write here
Relevant Equations
I didn't understand what I was supposed to write here
I came across the following question:
If g and f are uniform continuity functions In section I, then f + g uniform continuity In section I.
I was able to prove it with the help Triangle Inequality .
But I thought what would happen if they asked the same question for f-g
I'm sorry if my English isn't good and you don't understand me
 
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  • #2
Nothing should change to your proof. Check that up to minor modifications the same proof still works.

Alternatively, if you have proven that if ##f,g## is uniformly continuous, then also ##f+g## you can proceed as follows.

Show that ##h:= -g## is uniformly continuous (this will follow because ##|-x| = |x| \forall x \in \mathbb{R}## if you do the proof) and then you can apply what you already proved: ##f+h = f-g## will be uniformly continuous.
 
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  • #3
thank you
 
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sergey_le said:
thank you

Welcome to physicsforums btw! Hope you have a good time here.
 
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1. What is the definition of uniform continuity?

Uniform continuity of a function means that for any given value of epsilon, there exists a corresponding value of delta such that the difference between the function values at any two points within delta distance of each other is less than epsilon.

2. How do you prove uniform continuity of a function?

To prove uniform continuity, you must use the definition mentioned above and show that for any given epsilon, there exists a delta that satisfies the definition. This can be done by manipulating the function and using algebraic or calculus techniques.

3. What is the Triangle Inequality?

The Triangle Inequality states that for any three points on a plane, the distance between any two points is always less than or equal to the sum of the distances between the first and third point and the second and third point.

4. How does the Triangle Inequality relate to proving uniform continuity?

The Triangle Inequality is a useful tool when proving uniform continuity because it allows us to bound the difference between function values using distances between points. This helps us to find an appropriate delta value for a given epsilon.

5. Can proving uniform continuity be applied to any function?

No, not all functions are uniformly continuous. In order for a function to be uniformly continuous, it must be continuous and the limit of the function as x approaches infinity must be finite.

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