College Algebra (10th Edition)

Published by Pearson
ISBN 10: 0321979478
ISBN 13: 978-0-32197-947-6

Chapter 9 - Section 9.2 - Arithmetic Sequences - 9.2 Assess Your Understanding - Page 654: 55



Work Step by Step

The sequence is arithmetic with common difference d=2, $a_{1}=14.$ The sum $S_{n}$ of the first $n$ terms of $\left\{a_{n}\right\}$: $S_{n}=\displaystyle \frac{n}{2}\left[2a_{1}+(n-1)d\right]$ $S_{120}=\displaystyle \frac{120}{2}\left[2(14)+2(120-1)\right]$ $=60(226)=15,960$
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