College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter 8 - Sequences, Induction, and Probability - Exercise Set 8.3 - Page 740: 64

Answer

$a_{2}$ = -6 $a_{3}$ = 18

Work Step by Step

We know nth term $a_{n}$ = $a_{1}r^{n-1}$ Given Geometric sequence = 2, $a_{2}$, $a_{3}$, -54 $a_{1}$ = 2 $a_{4}$ = -54 From above $a_{4}$ = $2r^{4-1}$ = $2 r^{3}$ = -54 $r^{3}$ = -27 r = $\sqrt[3] (-27)$ = -3 $a_{2}$ = $a_{1}r^{2-1}$ = $2(-3)^{2-1}$ = 2$\times$(-3) = -6 $a_{3}$ = $a_{1} r^{3-1}$ = $2(-3)^{3-1}$ = $2 (-3)^{2}$ = 2$\times$9 = 18
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