Intermediate Algebra (6th Edition)

Published by Pearson
ISBN 10: 0321785045
ISBN 13: 978-0-32178-504-6

Chapter 11 - Section 11.1 - Sequences - Exercise Set - Page 640: 46

Answer

$a_{1}$ = 1 $a_{2}$ = 1

Work Step by Step

For the $n^{th}$ term of a Fibonacci Sequence, it is represented by $a_{n}$ = $\frac{1}{\sqrt{5}}[(\frac{1+\sqrt{5}}{2})^n$ - $(\frac{1-\sqrt{5}}{2})^n]$ So, for the first term, $a_{1}$ = $\frac{1}{\sqrt{5}}[(\frac{1+\sqrt{5}}{2})^1$ - $(\frac{1-\sqrt{5}}{2})^1]$ = $\frac{1}{\sqrt{5}}[\frac{1+\sqrt{5}}{2}$ - $(\frac{1-\sqrt{5}}{2})]$ = $\frac{1}{\sqrt{5}}[\frac{1+\sqrt{5}-1+\sqrt{5}}{2}]$ = $\frac{1}{\sqrt{5}}(\frac{2\sqrt{5}}{2})$ = $\frac{1}{\sqrt{5}} \cdot \sqrt{5}$ = 1 And, for the second term, $a_{2}$ = $\frac{1}{\sqrt{5}}[(\frac{1+\sqrt{5}}{2})^2$ - $(\frac{1-\sqrt{5}}{2})^2]$ = $\frac{1}{\sqrt{5}}[(\frac{1+\sqrt{5}}{2})$ + $(\frac{1-\sqrt{5}}{2})]$$[(\frac{1+\sqrt{5}}{2})$ - $(\frac{1-\sqrt{5}}{2})]$ = $\frac{1}{\sqrt{5}}(\frac{1+\sqrt{5}+1-\sqrt{5}}{2}) (\frac{1+\sqrt{5}-1+\sqrt{5}}{2})$ = $\frac{1}{\sqrt{5}}(\frac{2}{2})(\frac{2\sqrt{5}}{2})$ = $\frac{1}{\sqrt{5}} \cdot 1 \cdot \sqrt{5}$ = 1 Hence, the first two terms of a Fibonacci Sequence are each equal to 1.
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