Calculus (3rd Edition)

Published by W. H. Freeman
ISBN 10: 1464125260
ISBN 13: 978-1-46412-526-3

Chapter 2 - Limits - 2.9 The Formal Definition of a Limit - Exercises - Page 93: 27

Answer

$$ \lim_{x\to 1} f(x) =1$$

Work Step by Step

Let $\epsilon\gt0$ and let $\delta=\min \left(1, \frac{\epsilon}{2}\right) .$ Then, whenever $|x-1|\lt\delta,$ it follows that $0\lt x\lt 2 .$ If $1\lt x\lt 2$ then $\min \left(x, x^{2}\right)=x$ and $$ |f(x)-1|=|x-1|\lt\delta\lt \frac{\epsilon}{2}\lt \epsilon $$ On the other hand, if $0\lt x\lt 1,$ then $\min \left(x, x^{2}\right)=x^{2},|x+1|\lt 2$ and $$ |f(x)-1|=\left|x^{2}-1\right|=|x-1||x+1|\lt 2 \delta\lt \epsilon $$ Hence $$ \lim_{x\to 1} f(x) =1$$
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