Prove if abs|f(x)| <= B for all x#0, then lim as x->0 of xf(x) = 0,

  • Thread starter anthonyg
  • Start date
In summary, the conversation discusses how to prove that if there exists a number B such that the absolute value of f(x) is less than or equal to B for all values of x that are not equal to 0, then the limit of x times f(x) as x approaches 0 is equal to 0. The participants are discussing a direct δ-ε proof and the difficulties they are facing in starting the problem. They suggest looking at examples from class or notes to figure out the appropriate values for δ and ε.
  • #1
anthonyg
3
0
1. if there is a number B such that abs|f(x)| <= B for all x#0, then lim as x->0 of xf(x) = 0,2. Would I be able to get some help on how to prove this?3. Given Epsilon > 0 such that delta = epsilon/B will prove the limit equals 0. (I know that may not make much sense but how am I supposed to make a solution when I don't know where to start... but I was warned so here is my attempt.) :|
 
Last edited:
Physics news on Phys.org
  • #2
Welcome to PF .

It looks like a fairly direct δ-ε proof.

What have you tried?

Where are you stuck?
 
  • #3
Thanks, the thing is I don't know where to start. I mean my teacher always starts out with given ε > 0 such that δ... I honestly just don't know where to go either.
 
  • #4
anthonyg said:
Thanks, the thing is I don't know where to start. I mean my teacher always starts out with given ε > 0 such that δ... I honestly just don't know where to go either.
I think your teacher starts out with a given ε > 0, and then figures out what δ needs to be.

Look at your text or class notes for some examples.
 
  • #5
Oh, yea, thanks! I didn't think of that!
 

1. What is the statement "Prove if abs|f(x)| <= B for all x#0, then lim as x->0 of xf(x) = 0" trying to prove?

The statement is trying to prove that if the absolute value of a function f(x) is less than or equal to a constant B for all values of x except for x=0, then the limit of the product of x and f(x) as x approaches 0 is equal to 0.

2. How can this statement be proven?

This statement can be proven using the definition of a limit and the properties of absolute value and inequalities.

3. What does it mean for a function to have a limit as x approaches 0?

Having a limit as x approaches 0 means that the function approaches a specific value as x gets closer and closer to 0. In other words, the function's output becomes more and more predictable as x gets closer to 0.

4. What is the significance of the absolute value in this statement?

The absolute value is significant because it ensures that the function's output is always positive, even if the input is negative. This allows us to make conclusions about the behavior of the function without worrying about its sign.

5. How does this statement relate to the concept of continuity?

This statement is related to the concept of continuity because it shows that the function is continuous at x=0, meaning that the limit of the function at that point exists and is equal to the function's value at that point. This is an important property in the study of calculus and real analysis.

Similar threads

  • Calculus and Beyond Homework Help
Replies
5
Views
877
  • Calculus and Beyond Homework Help
Replies
9
Views
2K
  • Calculus and Beyond Homework Help
Replies
13
Views
2K
  • Calculus and Beyond Homework Help
Replies
2
Views
987
  • Calculus and Beyond Homework Help
Replies
2
Views
596
  • Calculus and Beyond Homework Help
Replies
2
Views
842
  • Calculus and Beyond Homework Help
Replies
5
Views
1K
  • Calculus and Beyond Homework Help
Replies
9
Views
547
  • Calculus and Beyond Homework Help
Replies
26
Views
2K
  • Calculus and Beyond Homework Help
Replies
26
Views
898
Back
Top