Use proof by contradiction to show that 2 is not a rational number. Note that you may use the theorem stated in question 14.

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
Topic Video
Question
**Proof by Contradiction: Showing that \(\sqrt{2}\) is Not a Rational Number**

To demonstrate that \(\sqrt{2}\) is not a rational number, we'll use a proof by contradiction. Assume that \(\sqrt{2}\) is rational, which means it can be expressed as a fraction \(\frac{a}{b}\) where \(a\) and \(b\) are integers with no common factors other than 1 (i.e., the fraction is in its simplest form) and \(b \neq 0\).

Start by expressing \(\sqrt{2}\) as:

\[
\sqrt{2} = \frac{a}{b}
\]

Squaring both sides, we have:

\[
2 = \frac{a^2}{b^2}
\]

This implies:

\[
a^2 = 2b^2
\]

From this equation, we can see that \(a^2\) is even because it equals \(2\) times an integer (\(b^2\)). Since \(a^2\) is even, \(a\) must also be even. Let \(a = 2k\) for some integer \(k\).

Substituting \(a = 2k\) into the equation \(a^2 = 2b^2\), we get:

\[
(2k)^2 = 2b^2
\]

\[
4k^2 = 2b^2
\]

\[
2k^2 = b^2
\]

This equation shows that \(b^2\) is even, which means \(b\) is also even.

Since both \(a\) and \(b\) are even, they have a common factor of \(2\). This contradicts our initial assumption that \(\frac{a}{b}\) was in its simplest form. Therefore, \(\sqrt{2}\) cannot be expressed as a fraction of two integers, proving that it is not a rational number.

*Note: You may use the theorem stated in question 14 to further justify this proof or explore related concepts.*
Transcribed Image Text:**Proof by Contradiction: Showing that \(\sqrt{2}\) is Not a Rational Number** To demonstrate that \(\sqrt{2}\) is not a rational number, we'll use a proof by contradiction. Assume that \(\sqrt{2}\) is rational, which means it can be expressed as a fraction \(\frac{a}{b}\) where \(a\) and \(b\) are integers with no common factors other than 1 (i.e., the fraction is in its simplest form) and \(b \neq 0\). Start by expressing \(\sqrt{2}\) as: \[ \sqrt{2} = \frac{a}{b} \] Squaring both sides, we have: \[ 2 = \frac{a^2}{b^2} \] This implies: \[ a^2 = 2b^2 \] From this equation, we can see that \(a^2\) is even because it equals \(2\) times an integer (\(b^2\)). Since \(a^2\) is even, \(a\) must also be even. Let \(a = 2k\) for some integer \(k\). Substituting \(a = 2k\) into the equation \(a^2 = 2b^2\), we get: \[ (2k)^2 = 2b^2 \] \[ 4k^2 = 2b^2 \] \[ 2k^2 = b^2 \] This equation shows that \(b^2\) is even, which means \(b\) is also even. Since both \(a\) and \(b\) are even, they have a common factor of \(2\). This contradicts our initial assumption that \(\frac{a}{b}\) was in its simplest form. Therefore, \(\sqrt{2}\) cannot be expressed as a fraction of two integers, proving that it is not a rational number. *Note: You may use the theorem stated in question 14 to further justify this proof or explore related concepts.*
Expert Solution
Step 1

Advanced Math homework question answer, step 1, image 1

steps

Step by step

Solved in 2 steps with 3 images

Blurred answer
Knowledge Booster
Propositional Calculus
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.
Similar questions
  • SEE MORE QUESTIONS
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,