Calculus: Early Transcendentals (2nd Edition)

Published by Pearson
ISBN 10: 0321947347
ISBN 13: 978-0-32194-734-5

Chapter 8 - Sequences and Infinite Series - 8.2 Sequences - 8.2 Exercises - Page 616: 55

Answer

$$0$$

Work Step by Step

Squeeze Theorem for sequence: Let us consider that $\{a_n\}$,$\{b_n\}$ and $\{c_n\}$ are sequences for a some number $K$. That is, $b_n \leq a_n \leq c_n$ for $n \gt K$ and $\lim\limits_{n \to \infty} b_n= \lim\limits_{n \to \infty} c_n=l$ Here, we have $a_n=\dfrac{\sin(n)}{2^n}$ Since, $-1 \leq \sin (n) \leq 1$; for all $n$. We will multiply $a_n$ by $\dfrac{1}{2^n}$ to obtain: $\dfrac{-1}{2^n} \leq \dfrac{\sin(n)}{2^n} \leq \dfrac{1}{2^n}$ As per Squeeze Theorem, we have $\{b_n\}=-\dfrac{1}{2^n}$ and $\{c_n\}=\dfrac{1}{2^n}$ Now, $\lim\limits_{n \to \infty} b_n=\lim\limits_{n \to \infty} (-\dfrac{1}{2^n})=0$ and $\lim\limits_{n \to \infty}c_n=\lim\limits_{n \to \infty} (\dfrac{1}{2^n})=0$ This implies that $\lim\limits_{n \to \infty} a_n=0$ by Squeeze Theorem for sequence.
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