Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 11 - Section 11.1 - Finding Limits Using Tables and Graphs - Exercise Set - Page 1139: 30

Answer

a) $\underset{x\to -{{3}^{-}}}{\mathop{\lim }}\,f\left( x \right)=2$, since, as x approaches $-3$ from the left, the value of $ f\left( x \right)$ gets closer to the y-coordinate of $2$. b) $\underset{x\to -{{3}^{+}}}{\mathop{\lim }}\,f\left( x \right)=2$, since, as x approaches $-3$ from the right, the value of $ f\left( x \right)$ gets closer to the y-coordinate of $2$. c) $\underset{x\to -3}{\mathop{\lim }}\,f\left( x \right)=2$, because both the left hand and right-hand limits are equal to 2. d) The function $ f\left( -3 \right)$ does not exist, because this point $\left( -3,2 \right)$ is shown by the open dot in the provided graph. e) $\underset{x\to {{0}^{-}}}{\mathop{\lim }}\,f\left( x \right)=0$, since, as x approaches 0 from the left, the value of $ f\left( x \right)$ gets closer to the y-coordinate of 0. f) $\underset{x\to {{0}^{+}}}{\mathop{\lim }}\,f\left( x \right)=3$, since, as x approaches 0 from the right, the value of $ f\left( x \right)$ gets closer to the y-coordinate of 3. g) $\underset{x\to 0}{\mathop{\lim }}\,f\left( x \right)$, does not exist, because the left hand and right-hand limits are unequal. h) $ f\left( 0 \right)$ does not exist, because this point is shown by the open dot in the provided graph. i) $\underset{x\to {{2}^{-}}}{\mathop{\lim }}\,f\left( x \right)=1$, since, as x approaches 2 from the left, the value of $ f\left( x \right)$ gets closer to the y-coordinate of 1. j) $\underset{x\to {{2}^{+}}}{\mathop{\lim }}\,f\left( x \right)=1$, since, as x approaches 2 from the right, the value of $ f\left( x \right)$ gets closer to the y-coordinate of 1. k) $\underset{x\to 2}{\mathop{\lim }}\,f\left( x \right)=1$, because both the left hand and right-hand limits are equal to 1. l) $ f\left( 2 \right)=-1$, because this point $\left( 2,-1 \right)$ is shown by the solid dot in the provided graph.

Work Step by Step

(a) Consider the provided limit $\underset{x\to -{{3}^{-}}}{\mathop{\lim }}\,f\left( x \right)$. To find $\underset{x\to -{{3}^{-}}}{\mathop{\lim }}\,f\left( x \right)$, examine the portion of the graph near $ x=-3$ but from the left. As x approaches $-3$ from the left, the value of $ f\left( x \right)$ gets closer to the y-coordinate of $2$. This point $\left( -3,2 \right)$ is shown by the open dot in the above graph. The point $\left( -3,2 \right)$ has a y-coordinate of 2. Thus, $\underset{x\to -{{3}^{-}}}{\mathop{\lim }}\,f\left( x \right)=2$. Hence, the value of $\underset{x\to -{{3}^{-}}}{\mathop{\lim }}\,f\left( x \right)$ is 2. (b) Consider the provided limit $\underset{x\to -{{3}^{+}}}{\mathop{\lim }}\,f\left( x \right)$. To find $\underset{x\to -{{3}^{+}}}{\mathop{\lim }}\,f\left( x \right)$, examine the portion of the graph near $ x=-3$ but from the right. As x approaches $-3$ from the right, the value of $ f\left( x \right)$ gets closer to the y-coordinate of $2$. This point $\left( -3,2 \right)$ is shown by the open dot in the above graph. The point $\left( -3,2 \right)$ has a y-coordinate of $2$. Thus, $\underset{x\to -{{3}^{+}}}{\mathop{\lim }}\,f\left( x \right)=2$. Hence, the value of $\underset{x\to -{{3}^{+}}}{\mathop{\lim }}\,f\left( x \right)$ is $2$ . (c) Consider the provided limit $\underset{x\to -3}{\mathop{\lim }}\,f\left( x \right)$. To find $\underset{x\to -{{3}^{+}}}{\mathop{\lim }}\,f\left( x \right)$, examine the portion of the graph near $ x=-3$ but from the right. As x approaches $-3$ from the right, the value of $ f\left( x \right)$ gets closer to the y-coordinate of $2$. This point $\left( -3,2 \right)$ is shown by the open dot in the above graph. The point $\left( -3,2 \right)$ has a y-coordinate of $2$. Thus, $\underset{x\to -{{3}^{+}}}{\mathop{\lim }}\,f\left( x \right)=2$. Hence, the value of $\underset{x\to -{{3}^{+}}}{\mathop{\lim }}\,f\left( x \right)$ is $2$. To find $\underset{x\to -{{3}^{-}}}{\mathop{\lim }}\,f\left( x \right)$, examine the portion of the graph near $ x=-3$ but from the left. As x approaches $-3$ from the left, the value of $ f\left( x \right)$ gets closer to the y-coordinate of $2$. This point $\left( -3,2 \right)$ is shown by the open dot in the above graph. The point $\left( -3,2 \right)$ has a y-coordinate of $2$. Thus, $\underset{x\to -{{3}^{-}}}{\mathop{\lim }}\,f\left( x \right)=2$. Hence, the value of $\underset{x\to -{{3}^{-}}}{\mathop{\lim }}\,f\left( x \right)$ is $2$. Since, $\underset{x\to -{{3}^{+}}}{\mathop{\lim }}\,f\left( x \right)=2$ and $\underset{x\to -{{3}^{-}}}{\mathop{\lim }}\,f\left( x \right)=2$. Here, both the left-hand limit and right-hand limit at $ x=-3$ are equal, Hence, $\underset{x\to -3}{\mathop{\lim }}\,f\left( x \right)=2$. (d) Consider the provided function, $ f\left( -3 \right)$. To find $ f\left( -3 \right)$, examine the portion of the graph near $ x=-3$. The graph of “f” at $ x=-3$ is shown by the open dot in the provided graph with coordinates $\left( -3,2 \right)$. Thus, the function $ f\left( -3 \right)$ does not exist. (e) Consider the provided limit $\underset{x\to {{0}^{-}}}{\mathop{\lim }}\,f\left( x \right)$. To find $\underset{x\to {{0}^{-}}}{\mathop{\lim }}\,f\left( x \right)$, examine the portion of the graph near $ x=0$ but from the left. As x approaches 0 from the left, the value of $ f\left( x \right)$ gets closer to the y-coordinate of 0. This point $\left( 0,0 \right)$ is shown by the open dot in the above graph. The point $\left( 0,0 \right)$ has a y-coordinate of 0. Thus, $\underset{x\to {{0}^{-}}}{\mathop{\lim }}\,f\left( x \right)=0$. Hence, the value of $\underset{x\to {{0}^{-}}}{\mathop{\lim }}\,f\left( x \right)$ is 0. (f) Consider the provided limit $\underset{x\to {{0}^{+}}}{\mathop{\lim }}\,f\left( x \right)$. To find $\underset{x\to {{0}^{+}}}{\mathop{\lim }}\,f\left( x \right)$, examine the portion of the graph near $ x=0$ but from the right. As x approaches 0 from the right, the value of $ f\left( x \right)$ gets closer to the y-coordinate of 3. This point $\left( 0,3 \right)$ is shown by the solid dot in the above graph. The point $\left( 0,3 \right)$ has a y-coordinate of 3. Thus $\underset{x\to {{0}^{+}}}{\mathop{\lim }}\,f\left( x \right)$. Hence, the value of $\underset{x\to {{0}^{+}}}{\mathop{\lim }}\,f\left( x \right)$ is 3. (g) Consider the provided limit $\underset{x\to 0}{\mathop{\lim }}\,f\left( x \right)$. To find $\underset{x\to {{0}^{+}}}{\mathop{\lim }}\,f\left( x \right)$, examine the portion of the graph near $ x=0$ but from the right. As x approaches 0 from the right, the value of $ f\left( x \right)$ gets closer to the y-coordinate of 3. This point $\left( 0,3 \right)$ is shown by the solid dot in the above graph. The point $\left( 0,3 \right)$ has a y-coordinate of 3. Thus $\underset{x\to {{0}^{+}}}{\mathop{\lim }}\,f\left( x \right)=3$. Hence, the value of $\underset{x\to {{0}^{+}}}{\mathop{\lim }}\,f\left( x \right)$ is 3. To find $\underset{x\to {{0}^{-}}}{\mathop{\lim }}\,f\left( x \right)$, examine the portion of the graph near $ x=0$ but from the left. As x approaches 0 from the left, the value of $ f\left( x \right)$ gets closer to the y-coordinate of 0. This point $\left( 0,0 \right)$ is shown by the open dot in the above graph. The point $\left( 0,0 \right)$ has a y-coordinate of 0. Thus, $\underset{x\to {{0}^{-}}}{\mathop{\lim }}\,f\left( x \right)=0$. Hence, the value of $\underset{x\to {{0}^{-}}}{\mathop{\lim }}\,f\left( x \right)$ is 0. Since, $\underset{x\to {{0}^{+}}}{\mathop{\lim }}\,f\left( x \right)=3$ and $\underset{x\to {{0}^{-}}}{\mathop{\lim }}\,f\left( x \right)=0$. Here, both the left-hand limit and right-hand limit at $ x=0$ are unequal, Hence, $\underset{x\to 0}{\mathop{\lim }}\,f\left( x \right)$ does not exist. (h) To find $ f\left( 0 \right)$, examine the portion of the graph near $ x=0$. The graph of “f” at $ x=0$ is shown by the open dot in the provided graph with coordinates $\left( 0,0 \right)$. Thus, the function $ f\left( 0 \right)$ does not exist. (i) Consider the provided limit $\underset{x\to {{2}^{-}}}{\mathop{\lim }}\,f\left( x \right)$. To find $\underset{x\to {{2}^{-}}}{\mathop{\lim }}\,f\left( x \right)$, examine the portion of the graph near $ x=2$ but from the left. As x approaches 2 from the left, the value of $ f\left( x \right)$ gets closer to the y-coordinate of 1. This point $\left( 2,1 \right)$ is shown by the open dot in the above graph. The point $\left( 2,1 \right)$ has a y-coordinate of 1. Thus, $\underset{x\to {{2}^{-}}}{\mathop{\lim }}\,f\left( x \right)=1$. Hence, the value of $\underset{x\to {{2}^{-}}}{\mathop{\lim }}\,f\left( x \right)$ is 1. (j) To find $\underset{x\to {{2}^{+}}}{\mathop{\lim }}\,f\left( x \right)$, examine the portion of the graph near $ x=2$ but from the right. As x approaches 2 from the right, the value of $ f\left( x \right)$ gets closer to the y-coordinate of 1. This point $\left( 2,1 \right)$ is shown by the open dot in the above graph. The point $\left( 2,1 \right)$ has a y-coordinate of 1. Thus, $\underset{x\to {{2}^{+}}}{\mathop{\lim }}\,f\left( x \right)=1$. Hence, the value of $\underset{x\to {{2}^{+}}}{\mathop{\lim }}\,f\left( x \right)$ is 1. (k) Consider the provided limit $\underset{x\to 2}{\mathop{\lim }}\,f\left( x \right)$. To find $\underset{x\to {{2}^{+}}}{\mathop{\lim }}\,f\left( x \right)$, examine the portion of the graph near $ x=2$ but from the right. As x approaches 2 from the right, the value of $ f\left( x \right)$ gets closer to the y-coordinate of 1. This point $\left( 2,1 \right)$ is shown by the open dot in the above graph. The point $\left( 2,1 \right)$ has a y-coordinate of 1. Thus, $\underset{x\to {{2}^{+}}}{\mathop{\lim }}\,f\left( x \right)=1$. Hence, the value of $\underset{x\to {{2}^{+}}}{\mathop{\lim }}\,f\left( x \right)$ is 1. . To find $\underset{x\to {{2}^{-}}}{\mathop{\lim }}\,f\left( x \right)$, examine the portion of the graph near $ x=2$ but from the left. As x approaches 2 from the left, the value of $ f\left( x \right)$ gets closer to the y-coordinate of 1. This point $\left( 2,1 \right)$ is shown by the open dot in the above graph. The point $\left( 2,1 \right)$ has a y-coordinate of 1. Thus, $\underset{x\to {{2}^{-}}}{\mathop{\lim }}\,f\left( x \right)=1$. Hence, the value of $\underset{x\to {{2}^{-}}}{\mathop{\lim }}\,f\left( x \right)$ is 1. Since, $\underset{x\to {{2}^{+}}}{\mathop{\lim }}\,f\left( x \right)=1$ and $\underset{x\to {{2}^{-}}}{\mathop{\lim }}\,f\left( x \right)=1$, here both the right hand and left-hand limit is the same at $ x=2$. Hence, $\underset{x\to 2}{\mathop{\lim }}\,f\left( x \right)=1$ (l) Consider the provided function, $ f\left( 2 \right)$. To find $ f\left( 2 \right)$, examine the portion of the graph near $ x=2$. The graph of “f” at $ x=2$ is shown by the solid dot in the provided graph with coordinates $\left( 2,-1 \right)$. Thus, $ f\left( 2 \right)=-1$
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