91Ó°ÊÓ

What is the geometric mean of 8 and 18\(?\) $$ \begin{array}{lllll}{\text { F. } 12} & {\text { G. } 13} & {\text { H. } 26} & {\text { J. } 36}\end{array} $$

Find the missing terms of each arithmetic sequence. (Hint: The arithmetic mean of the first and fifth terms is the third term.)

Find the missing terms of each arithmetic sequence. (Hint: The arithmetic mean of the first and fifth terms is the third term.)

Write an explicit and a recursive formula for each arithmetic sequence. $$ -3,0,3,6, \dots $$

Decide whether each formula is explicit or recursive. Then find the first five terms of each sequence. \(a_{n}=3 n(n+1)\)