Chapter 2: Problem 14
Modify the argument in Theorem \(2.4 .7\) to show that there exists a positive real number \(y\) such that \(y^{2}=3\)
/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none}
Learning Materials
Features
Discover
Chapter 2: Problem 14
Modify the argument in Theorem \(2.4 .7\) to show that there exists a positive real number \(y\) such that \(y^{2}=3\)
All the tools & learning materials you need for study success - in one app.
Get started for free
(a) Show that if \(x, y\) are rational numbers, then \(x+y\) and \(x y\) are rational numbers. (b) Prove that if \(x\) is a rational number and \(y\) is an irrational number, then \(x+y\) is an irrational number. If, in addition, \(x \neq 0\), then show that \(x y\) is an irrational number.
If \(y>0\), show that there exists \(n \in \mathbb{N}\) such that \(1 / 2^{n}
Let \(S\) be a nonempty bounded set in \(\mathbb{R}\). (a) Let \(a>0\), and let \(a S:=\\{\) as: \(s \in S\\}\). Prove that $$ \inf (a S)=a \inf S, \quad \sup (a S)=a \sup S $$ (b) Let \(b<0\) and let \(b S=\\{b s: s \in S\\}\). Prove that $$ \inf (b S)=b \sup S, \quad \sup (b S)=b \inf S $$
Let \(S_{3}=\\{1 / n: n \in \mathbb{N}\\} .\) Show that sup \(S_{3}=1\) and inf \(S_{3} \geq 0 .\) (It will follow from the Archimedean Property in Section \(2.4\) that inf \(\left.S_{3}=0 .\right)\)
What do you think about this solution?
We value your feedback to improve our textbook solutions.