Precalculus (6th Edition)

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

Chapter 11 - Further Topics in Algebra - 11.2 Arithmetic Sequences and Series - 11.2 Exercises - Page 1025: 60



Work Step by Step

$$ S_{n}=2+4+6+8+...+2n\Rightarrow S_{70}=2+4+6+\ldots +140\Rightarrow a_{1}=2;a_{70}=140\Rightarrow S_{n}=\dfrac {a_{1}+a_{n}}{2}\times n\Rightarrow S_{70}=\dfrac {2+140}{2}\times 70=4970$$
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