Algebra 2 (1st Edition)

Published by McDougal Littell
ISBN 10: 0618595414
ISBN 13: 978-0-61859-541-9

Chapter 12 Sequences and Series - 12.2 Analyze Arithmetic Sequences and Series - Guided Practice for Examples 5 and 6 - Page 805: 6


$108$ cards.

Work Step by Step

Given the rule for the number of cards in the n-th row in example 6, $a_{n}=3n$, The formula for the sum of a finite series is $S_{n}=n\displaystyle \cdot\frac{a_{1}+a_{n}}{2}$. We first find $a_{1}$ and $a_{8}$. $a_{1}=3\cdot 1=3$ $a_{8}=3\cdot 8=24.$ Substitute these values into the formula for $S_{8}$. $S_{8}=8\displaystyle \cdot\frac{3+24}{2}=4\cdot 27=108$
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