Trouble with Delta Epsilon Problem

In summary, there is no value of delta greater than 0 that satisfies the problem because the set of x satisfying 0<|x-1|<delta always has elements for which |f(x)-4| is equal to or greater than 2, specifically those x that are between 0 and 1. This means that no matter what neighborhood of 1 is chosen, there will always be elements smaller than 1 for which the value of f is less than or equal to 2, resulting in a distance to 4 that is greater than 1. As for part (b), it is not a sentence to prove due to x being a free variable.
  • #1
tfeuerbach
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I understand and can do part (a) of the problem but when it gets to part (b) I'm lost, how do I find/explain why there is no value of delta > 0 that satisfies the the problem.
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  • #2
tfeuerbach said:
how do I find/explain why there is no value of delta > 0 that satisfies the the problem.
Because the set of $x$ satisfying $0<|x-1|<\delta$ (the deleted neighborhood of 1) always has elements for which $|f(x)-4|\ge2$: namely, those $x$ that lie between 0 and 1. Whichever neighborhood of 1 you choose, it will always have elements smaller than 1, and for those elements the value of $f$ is $\le 2$, so its distance to 4 is greater than 1.
 
  • #3
Part (b) is not a sentence to prove because \(\displaystyle x\) is free.

(b) Explain why there can be no value of \(\displaystyle \delta>0\) such that for all \(\displaystyle x\in [0,\ 2]\) if \(\displaystyle 0<|x-1|<\delta\), then \(\displaystyle |f(x)-4|<1\).

Now this is a sentence to prove.
 

1. What is the "Trouble with Delta Epsilon Problem"?

The "Trouble with Delta Epsilon Problem" is a mathematical problem that involves finding the limit of a function using the concept of delta and epsilon. It is commonly encountered in calculus and real analysis courses.

2. Why is the "Trouble with Delta Epsilon Problem" important?

The "Trouble with Delta Epsilon Problem" is important because it helps to develop an understanding of the fundamental concepts of limits, continuity, and convergence in mathematics. It also serves as a basis for more advanced topics in calculus and analysis.

3. What are delta and epsilon?

Delta and epsilon are mathematical symbols used to represent small quantities or differences. In the context of the "Trouble with Delta Epsilon Problem", delta represents a small change in the input of a function, while epsilon represents a small tolerance for the output of the function.

4. How do you solve the "Trouble with Delta Epsilon Problem"?

To solve the "Trouble with Delta Epsilon Problem", one must show that for any given epsilon, there exists a corresponding delta such that the output of the function is within the tolerance of epsilon. This can be done by manipulating the function and using algebraic and logical arguments.

5. What are some common misconceptions about the "Trouble with Delta Epsilon Problem"?

One common misconception about the "Trouble with Delta Epsilon Problem" is that it is only applicable to real numbers. In fact, the problem can also be applied to functions with complex numbers. Another misconception is that it is a difficult problem, when in reality it is a fundamental concept that can be broken down into smaller, manageable steps.

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