1. In this exercise we give an alternate proof that Q+, the set of positive rational num- bers, is denumerable. (a) Define f : Q+ → N by f(r) = 2°3°, where r = 1. What is f(8/10)? What is f (10/2)? (b) Is f onto? Justify your answer. (c) Prove that f is one-to-one. (d) Let S be the range of f. Why is S denumerable? (e) Use parts (c) and (d) to argue that Q+ is denumerable. a/b with a, b eN and gcd(a, b) %3D

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
Problem 1RQ
icon
Related questions
icon
Concept explainers
Question
**Theorem 0.1. (Fundamental Theorem of Arithmetic)** Any integer \( n > 2 \) can be expressed as a product of prime numbers, and this expression is unique up to the order of the prime factors.

**Theorem 0.2.** Suppose \( T \) is a denumerable set and \( S \) is an infinite subset of \( T \). Then \( S \) is also denumerable.

1. In this exercise, we give an alternate proof that \( \mathbb{Q}^+ \), the set of positive rational numbers, is denumerable.
   (a) Define \( f : \mathbb{Q}^+ \rightarrow \mathbb{N} \) by \( f(r) = 2^a 3^b \), where \( r = a/b \) with \( a, b \in \mathbb{N} \) and \(\gcd(a, b) = 1\).
      1. What is \( f(8/10) \)? What is \( f(10/2) \)?
   (b) Is \( f \) onto? Justify your answer.
   (c) Prove that \( f \) is one-to-one.
   (d) Let \( S \) be the range of \( f \). Why is \( S \) denumerable?
   (e) Use parts (c) and (d) to argue that \( \mathbb{Q}^+ \) is denumerable.
Transcribed Image Text:**Theorem 0.1. (Fundamental Theorem of Arithmetic)** Any integer \( n > 2 \) can be expressed as a product of prime numbers, and this expression is unique up to the order of the prime factors. **Theorem 0.2.** Suppose \( T \) is a denumerable set and \( S \) is an infinite subset of \( T \). Then \( S \) is also denumerable. 1. In this exercise, we give an alternate proof that \( \mathbb{Q}^+ \), the set of positive rational numbers, is denumerable. (a) Define \( f : \mathbb{Q}^+ \rightarrow \mathbb{N} \) by \( f(r) = 2^a 3^b \), where \( r = a/b \) with \( a, b \in \mathbb{N} \) and \(\gcd(a, b) = 1\). 1. What is \( f(8/10) \)? What is \( f(10/2) \)? (b) Is \( f \) onto? Justify your answer. (c) Prove that \( f \) is one-to-one. (d) Let \( S \) be the range of \( f \). Why is \( S \) denumerable? (e) Use parts (c) and (d) to argue that \( \mathbb{Q}^+ \) is denumerable.
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 2 steps with 2 images

Blurred answer
Knowledge Booster
Application of Differentiation
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, advanced-math and related others by exploring similar questions and additional content below.
Recommended textbooks for you
Advanced Engineering Mathematics
Advanced Engineering Mathematics
Advanced Math
ISBN:
9780470458365
Author:
Erwin Kreyszig
Publisher:
Wiley, John & Sons, Incorporated
Numerical Methods for Engineers
Numerical Methods for Engineers
Advanced Math
ISBN:
9780073397924
Author:
Steven C. Chapra Dr., Raymond P. Canale
Publisher:
McGraw-Hill Education
Introductory Mathematics for Engineering Applicat…
Introductory Mathematics for Engineering Applicat…
Advanced Math
ISBN:
9781118141809
Author:
Nathan Klingbeil
Publisher:
WILEY
Mathematics For Machine Technology
Mathematics For Machine Technology
Advanced Math
ISBN:
9781337798310
Author:
Peterson, John.
Publisher:
Cengage Learning,
Basic Technical Mathematics
Basic Technical Mathematics
Advanced Math
ISBN:
9780134437705
Author:
Washington
Publisher:
PEARSON
Topology
Topology
Advanced Math
ISBN:
9780134689517
Author:
Munkres, James R.
Publisher:
Pearson,