University Calculus: Early Transcendentals (3rd Edition)

Published by Pearson
ISBN 10: 0321999584
ISBN 13: 978-0-32199-958-0

Chapter 2 - Section 2.5 - Continuity - Exercises - Page 94: 9

Answer

For $f$ to be continuous at $x=2$, $f(2)$ should be assigned value $0$.

Work Step by Step

To make $f$ continuous at $x=2$, $f(2)$ must acquire a value so that $\lim_{x\to2}f(x)=f(2)$. That means we need to calculate $\lim_{x\to2}f(x)$ and assign that value to $f(2)$. - As $x\to2^-$, since $x\lt2$, we employ the function $f(x)=-2x+4$ $$\lim_{x\to2^-}f(x)=\lim_{x\to2^-}(-2x+4)=-2\times2+4=0$$ - As $x\to2^+$, since $x\gt2$, we employ the function $f(x)=0$ $$\lim_{x\to2^+}f(x)=\lim_{x\to2^+}0=0$$ Therefore, $\lim_{x\to2}f(x)=\lim_{x\to2^+}f(x)=\lim_{x\to2^-}f(x)=0$ So, for $f$ to be continuous at $x=2$, $f(2)$ should be assigned value $0$ as well.
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