Answer
$S_{7}=70$
Work Step by Step
$a_1=1$ and $a_n=a_7=19$
$S_n=\frac{n}{2}(a_1+a_n)$
$S_{7}=\frac{7}{2}(1+19)=\frac{7}{2}(20)=\frac{140}{2}=70$
Algebra and Trigonometry 10th Edition
by Larson, Ron
Published by
Cengage Learning
ISBN 10:
9781337271172
ISBN 13:
978-1-33727-117-2
Chapter 11 - 11.2 - Arithmetic Sequences and Partial Sums - 11.2 Exercises - Page 786: 46
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.
