The sum, Sn , of the first n terms of an arithmetic sequence is given by Sn = n 2 (a1 +

Chapter 5, Problem 121

(choose chapter or problem)

The sum, \(S_{n}\), of the first n terms of an arithmetic sequence is given by

\(S_{n}=\frac{n}{2}\left(a_{1}+a_{n}\right)\),

in which \(a_{1}\) is the first term and \(a_{n}\) is the nth term. The sum, \(S_{n}\), of the first n terms of a geometric sequence is given by

\(S_{n}=\frac{a_{1}\left(1-r^{n}\right)}{1-r}\),

in which \(a_{1}\) is the first term and r is the common ratio \((r \neq 1)\). In Exercises 115-122, determine whether each sequence is arithmetic or geometric. Then use the appropriate formula to find \(S_{10}\), the sum of the first ten terms.

-10, -6, -2, 2,...

Text Transcription:

S_n

S_n=n/2(a_1+a_n)

a_1

a_n

S_n=a_1(1-r^n)/1-r

(r neq 1)

S_10