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: 71



Work Step by Step

$\sum ^{12}_{i=4}\left( -5-8i\right) =\dfrac {n}{2}\times \left( a_{4}+a_{12}\right) \Rightarrow a_{4}=-5-8\times 4=-45;a_{12}=-5-8\times 12=-101\Rightarrow S=\dfrac {9\times \left( -45+\left( -101\right) \right) }{2}=-657$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.