Calculus with Applications (10th Edition)

Published by Pearson
ISBN 10: 0321749006
ISBN 13: 978-0-32174-900-0

Chapter 3 - The Derivative - 3.2 Continuity - 3.2 Exercises - Page 147: 5

Answer

The function $f(x)$ is discontinuous at $x=-5$ and $x=0$ (a) $f(-5)$ does not exist. $f(0) $ does not exist. (b) $$ \lim _{x \rightarrow-5^{-}} f(x)=\infty \quad \quad \text {(limit does not exist) } $$ and $$ \lim _{x \rightarrow 0^{-}} f(x)=0 $$ (c) $$ \lim _{x \rightarrow-5^{+}} f(x)=-\infty \quad \quad \text {(limit does not exist) } $$ and $$ \lim _{x \rightarrow 0^{+}} f(x)=0 $$ (d) Since $$ \lim _{x \rightarrow-5^{-}} f(x) \ne \lim _{x \rightarrow-5^{+}} f(x) $$ then, $$ \lim _{x \rightarrow-5} f(x) \quad \quad \text {(does not exist) } $$ and $$ \lim _{x \rightarrow 0^{-}} f(x)=\lim _{x \rightarrow 0^{+}} f(x)=0 $$ then, $$ \lim _{x \rightarrow0} f(x)=0. $$ (e) $f(-5)$ does not exist. $$ \lim _{x \rightarrow-5} f(x) \quad \quad \text {(does not exist) } $$ $f(0) $ does not exist.

Work Step by Step

The function $f(x)$ is discontinuous at $x=-5$ and $x=0$ (a) $f(-5)$ does not exist. $f(0) $ does not exist. (b) $$ \lim _{x \rightarrow-5^{-}} f(x)=\infty \quad \quad \text {(limit does not exist) } $$ and $$ \lim _{x \rightarrow 0^{-}} f(x)=0 $$ (c) $$ \lim _{x \rightarrow-5^{+}} f(x)=-\infty \quad \quad \text {(limit does not exist) } $$ and $$ \lim _{x \rightarrow 0^{+}} f(x)=0 $$ (d) Since $$ \lim _{x \rightarrow-5^{-}} f(x) \ne \lim _{x \rightarrow-5^{+}} f(x) $$ then, $$ \lim _{x \rightarrow-5} f(x) \quad \quad \text {(does not exist) } $$ and $$ \lim _{x \rightarrow 0^{-}} f(x)=\lim _{x \rightarrow 0^{+}} f(x)=0 $$ then, $$ \lim _{x \rightarrow0} f(x)=0. $$ (e) $f(-5)$ does not exist. $$ \lim _{x \rightarrow-5} f(x) \quad \quad \text {(does not exist) } $$ $f(0) $ does not exist.
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