Calculus 8th Edition

Published by Cengage
ISBN 10: 1285740629
ISBN 13: 978-1-28574-062-1

Chapter 11 - Infinite Sequences and Series - 11.1 Sequences - 11.1 Exercises - Page 744: 8

Answer

$-\frac{1}{2},\frac{2}{3},-\frac{3}{7},\frac{4}{25},-\frac{5}{121}$

Work Step by Step

To find the first five terms of the sequence $a_n = \frac{(-1)^{(n)} n}{n!+1}$, we must plug in $n=1, n=2, n=3, n=4,$ and $n=5.$ $a_1 = \frac{(-1)^{1}\times 1}{1!+1}=\frac{-1}{1+1}=-\frac{1}{2}$ $a_2 =\frac{(-1)^{2} \times 2}{2!+1}=\frac{2}{2+1}=\frac{2}{3}$ $a_3 = \frac{(-1)^{3} \times 3}{3!+1}=-\frac{3}{6+1}=-\frac{3}{7}$ $a_4 =\frac{(-1)^{4} \times 4}{4!+1}=\frac{4}{24+1}=\frac{4}{25}$ $a_5 = \frac{(-1)^{5} \times 5}{5!+1}=\frac{-5}{120+1}=-\frac{5}{121}$ Hence we see that the first five terms are $-\frac{1}{2},\frac{2}{3},-\frac{3}{7},\frac{4}{25},-\frac{5}{121}$
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