## Quick Reference

A finite or infinite sequence *a*_{1}, *a*_{2}, *a*_{3},… with a common ratio *r*, so that *a*_{2}/*a*_{1}=*r*, *a*_{3}/*a*_{2}=*r*,…. The first term is usually denoted by *a*. For example, 3, 6, 12, 24, 48,…is the geometric sequence with *a*=3, *r*=2. In such a geometric sequence, the *n*-th term *a*_{n} is given by *a*_{n}=*ar*^{n−1}.

http://www.articlesforeducators.com/dir/mathematics/sequences_series/chess_problem.asp Stories illustrating the dramatic behaviour of geometric sequences.

*Subjects:*
Mathematics.