Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 11 - Further Topics in Algebra - 11.2 Arithmetic Sequences and Series - 11.2 Exercises - Page 1024: 26


$a_n=5n-9$ $a_8=31$

Work Step by Step

$a_1=-4, a_5=16$ Determine $d$: $a_n=a_1+(n-1)d$ $a_5=a_1+(5-1)d$ $16=-4+4d$ $20=4d$ $d=5$ $a_n=a_1+(n-1)d$ $a_n=-4+(n-1)*5$ $a_n=-4+5n-5$ $\boxed{a_n=5n-9}$ $a_8=5*8-9$ $a_8=40-9$ $\boxed{a_8=31}$
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