Calculus: Early Transcendentals 8th Edition

Published by Cengage Learning
ISBN 10: 1285741552
ISBN 13: 978-1-28574-155-0

Chapter 2 - Section 2.4 - The Precise Definition of a Limit - 2.4 Exercises - Page 114: 37

Answer

$\lim\limits_{x \to a} \sqrt{x}= \sqrt{a}~~~$ if $a \gt 0$

Work Step by Step

Suppose that $a \gt 0$ Let $\epsilon \gt 0$ be given. Let $\delta = \sqrt{a}~\epsilon$ Suppose that $\vert x-a \vert \lt \delta$ Then: $\vert \sqrt{x}-\sqrt{a} \vert = \frac{\vert x-a \vert}{\sqrt{x}+\sqrt{a}} \lt \frac{\delta}{\sqrt{x}+\sqrt{a}} \lt \frac{\delta}{\sqrt{a}} = \frac{\sqrt{a}~\epsilon}{\sqrt{a}}=\epsilon$ Therefore, $\lim\limits_{x \to a} \sqrt{x}= \sqrt{a}~~~$ if $a \gt 0$
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