Answer
$-3180$
Work Step by Step
$S_{n}=\dfrac {n}{2}\left( 2a+\left( n-1\right) d\right) =\dfrac {30}{2}\left( 2\times 10+\left( 30-1\right) \times \left( -8\right) \right) =15\times \left( 20-8\times 29\right) =-3180$
Precalculus: Mathematics for Calculus, 7th Edition
by Stewart, James; Redlin, Lothar; Watson, Saleem
Published by
Brooks Cole
ISBN 10:
1305071751
ISBN 13:
978-1-30507-175-9
Chapter 12 - Section 12.2 - Arithmetic Sequences - 12.2 Exercises - Page 857: 52
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