Answer
$1170$
Work Step by Step
$S_{n}=\dfrac {n}{2}\left( a+\left( n-1\right) d\right) =\dfrac {15}{2}\left( -40+\left( 15-1\right) \times 14\right) =\dfrac {15}{2}\times 156=1170$
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: 53
Update this answer!
You can help us out by revising, improving and updating this answer.
Update this answerAfter 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.
