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

Chapter 5, Problem 115

(choose chapter or problem)

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

\(S_n = \frac{n}{2} (a_1 + a_n)\),

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

\(S_n = \frac{a_1(1 - r^n )}{1 - r}\),

in which \(a_1\) is the first term and r is the common ratio \((r \ne 1)\). Determine whether each sequence is arithmetic or geometric. Then use the appropriate formula to find \(S_{10}\), the sum of the first ten terms.

4, 10, 16, 22, . . .