Precalculus (6th Edition)

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

Chapter 11 - Further Topics in Algebra - 11.3 Geometric Sequences and Series - 11.3 Exercises: 19

Answer

$a_{5}=a_{1}\times r^{4}=-9\times \left( -3\right) ^{4}=-729;$ $a_{n}=a_{1}\times r^{n-1}=\left( -9\right) \times \left( -3\right) ^{n-1}$

Work Step by Step

$a_{1}=\dfrac {a_{4}}{r^{3}}=\dfrac {243}{\left( -3\right) ^{3}}=-9;a_{5}=a_{1}\times r^{4}=-9\times \left( -3\right) ^{4}=-729;a_{n}=a_{1}\times r^{n-1}=\left( -9\right) \times \left( -3\right) ^{n-1}$
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