College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter 8, Sequences and Series - Section 8.3 - Geometric Sequences - 8.3 Exercises: 61

Answer

$S_6=-105$

Work Step by Step

We need to find: $\sum_{k=1}^{6}5(-2)^{k-1}$ We see that this is a geometric sequence with $a=5$ and $r=-2$. We know the partial sum of a geometric sequence is: $S_n=a_1\frac{1-r^n}{1-r}$ $S_6=5\frac{1-(-2)^{6}}{1-(-2)}=-105$
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.