Algebra 1: Common Core (15th Edition)

Published by Prentice Hall
ISBN 10: 0133281140
ISBN 13: 978-0-13328-114-9

Chapter 7 - Exponents and Exponential Functions - 7-8 Geometric Sequences - Practice and Problem-Solving Exercises - Page 470: 28


The recursive formula is $a_{1}$=4 and $a_{n}$=$a_{n-1}$ $\times$ 2.

Work Step by Step

Use the recursive formula $a_{1}$=1, $a_{n}$=$a_{n-1}$$\times$r. The starting value is 4, so it is the $a_{1}$. You have the sequence 4,8,16 so use the common ratio formula(r=$\frac{{a_{2}}}{{a_{1}}}$) r=$\frac{8}{4}$=2 and r=$\frac{16}{8}$=2.So the common ratio is 2.Substitute the value of a1 and R into the recursive formula: The recursive formula is $a_{1}$=4 and $a_{n}$=$a_{n-1}$ $\times$ 2.
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