Knowee
Questions
Features
Study Tools

show that any bounded subset of R is totally bounded . is this true in R^n? can you make the same statement in any metric space?

Question

Show that any bounded subset of R \mathbb{R} is totally bounded. Is this true in Rn \mathbb{R}^n ? Can you make the same statement in any metric space?

🧐 Not the exact question you are looking for?Go ask a question

Solution

Sure, let's go through this step by step.

  1. Show that any bounded subset of R is totally bounded:

A set S in R is bounded if there exists a real number M such that |x| ≤ M for all x in S. Now, let's show that S is totally bounded. By definition, a set is totally bounded if for every ε > 0, there exists a finite number of balls of radius ε that can cover the set.

Since S is bounded, there exists a ball B(M) of radius M that can cover S. Now, for any ε > 0, we can always find a finite number of balls of radius ε that can cover B(M), and hence cover S. This is because the real line R is Archimedean, meaning for any real numbers x and y with x > 0, there exists a natural number n such that nx > y. In this case, we can always find a natural number n such that nε > 2M, meaning we can cover B(M) with n balls of radius ε. Therefore, any bounded subset of R is totally bounded.

  1. Is this true in R^n?

Yes, this is also true in R^n. The proof is similar. A set S in R^n is bounded if there exists a real number M such that ||x|| ≤ M for all x in S, where ||x|| denotes the Euclidean norm. For any ε > 0, we can always find a finite number of balls of radius ε that can cover the ball B(M) of radius M, and hence cover S. This is because R

This problem has been solved

Similar Questions

Give an example of a bounded non-empty set of real numbers which hasa supremum, but does not have a maximum. Justify your answercarefully.

Let (xn) be a bounded sequence in R. Show that there exist subsequences (xnk ) and(xmk ) of (xn) such thatlimk→∞ xnk = lim sup xn and limk→∞ xmk = lim inf xn.

Show that any open interval (a, b) in R is an open ball. Is R an open ball in R

8. Let (X, d) be a metric space and let S ⊆ X. Prove that dS (x) = 0 if and only if x ∈ S

Give an example of a function that is uniformly continuous on R but is not bounded on R.

1/1

Upgrade your grade with Knowee

Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.