1. Section 2 – Geometric Sequences and Series
Chapter 12
Section 2 – Geometric Sequences and Series

2. Geometric Sequence
A geometric sequence is a sequence of terms that are multiplied by a ratio to get to consecutive terms.
This ratio is called the common ratio and is denoted with an r.
For example: 3, 1, 1/3, 1/9,... is a geometric sequence with a common ratio of r = 1/3

3. The nth term
The nth term of a geometric sequence with first term a1 and common ratio r is given by an = a1(rn-1)
The sum of the first n terms of a finite geometric series is given by the formula:
Sn = (a1 - a1rn)/(1-r)

4. Examples
EX 1: Find the sum of the first ten terms of the geometric series:
16 – –

5. Assignment
Chapter 12, Section 2
pgs #16-32E,42,48