Answer
4970
Work Step by Step
$$ S_{n}=2+4+6+8+...+2n\Rightarrow S_{70}=2+4+6+\ldots +140\Rightarrow a_{1}=2;a_{70}=140\Rightarrow S_{n}=\dfrac {a_{1}+a_{n}}{2}\times n\Rightarrow S_{70}=\dfrac {2+140}{2}\times 70=4970$$
Precalculus (6th Edition)
by Lial, Margaret L.; Hornsby, John; Schneider, David I.; Daniels, Callie
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
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