Simple analysis continuity problem

In summary, if a real function f is continuous at a point a and f(a)<M for some M, then there exists an open interval I containing a such that f(x)<M for all x in I. This can be proven using the extreme value theorem, intermediate value theorem, and the definition of continuity. By drawing out the scenario, we can see that the continuity of f guarantees that we can make f(x) within a certain distance of f(a), ensuring that M will also be a bound for f(x). This explanation may help clarify the problem for those new to this concept.
  • #1
economist1985
8
0

Homework Statement


If f is a real function which is continuous at a element R and if f(a)<M for some M element of R, prove that there is an open interval I containing a such that f(x)<M for all x element of I.


Homework Equations


Extreme value theorem, intermediate value theorem, definition of continuity


The Attempt at a Solution


I have no idea how to solve this.
 
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  • #2
Draw out the scenario. You have a continuous function with some point a on the x-axis, f(a) on the y-axis. Draw a horizontal line through the point f(a). We can think of M as a horizontal line somewhere above f(a). Let D be the distance between f(a) and M. If we can make f(x) within D of f(a), then M will be a bound for f(x) as well. But this is guaranteed by the continuity of f (epsilon-delta definition).
 
  • #3
Thanks for the explanation. The problem is clearer now to me. What I still do not get is how the epsilon delta definition guarantees it. ?? Sorry if I can't follow through... I'm new to this.
 
  • #4
Oh I think I got it. Thanks
 

Related to Simple analysis continuity problem

1. What is a simple analysis continuity problem?

A simple analysis continuity problem is a mathematical concept that involves finding the limit of a function as its input approaches a specific value. It is used to determine if a function is continuous at a certain point.

2. How is continuity defined in simple analysis?

In simple analysis, continuity is defined as a property of a function where the output value of the function approaches the same value as the input value approaches a specific point. This means that there are no sudden jumps or breaks in the function's graph.

3. What is the importance of studying simple analysis continuity problems?

Studying simple analysis continuity problems is important because it helps us understand the behavior of functions and their graphs. It also allows us to determine if a function is continuous or not, which is essential in many applications of mathematics and science.

4. What are the common techniques used to solve simple analysis continuity problems?

Some common techniques used to solve simple analysis continuity problems include direct substitution, factoring, and using the limit laws. Other methods such as L'Hôpital's rule and the squeeze theorem can also be used in more complex cases.

5. Are there real-world applications of simple analysis continuity problems?

Yes, simple analysis continuity problems have real-world applications in various fields such as physics, engineering, and economics. For example, in physics, continuity is essential in understanding the motion of objects and their trajectories. In economics, continuity is used to analyze the relationship between variables such as supply and demand.

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