Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 12 - Section 12.2 - Arithmetic Sequences - 12.2 Exercises - Page 857: 42


$d=-2.7$ $a_{n}=17.7-2.7n $ $ a_{5}=4.2;$ $a_{100}=-252.3$

Work Step by Step

$d=a_{n+1}-a_{n}=12.3-15=9.6-12.3=6.9-9.6=-2.7$ $a_{n}=a+\left( n-1\right) d\Rightarrow a_{1}=a+\left( 1-1\right) d=a=15$ $a_{n}=a+\left( n-1\right) d=15+\left( n-1\right) \times \left( -2.7\right) =15-2.7n+2.7=17.7-2.7n$ $a_{n}=17.7-2.7n\Rightarrow a_{5}=17.7-2.7\times 5=4.2;a_{100}=17.7-2.7\times 100=-252.3$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.