## SAT SUBJECT TEST MATH LEVEL 2

## PART 2

## REVIEW OF MAJOR TOPICS

## CHAPTER 3

## Numbers and Operations

3.4 Sequences and Series

### GEOMETRIC SEQUENCES

Another common type of sequence studied at this level is a geometric sequence (or geometric progression). In a geometric sequence the ratio of any two successive terms is a constant *r* called the constant ratio. The first *n* terms of a geometric sequence can be denoted by

*t*_{1}, *t*_{1}*r*, *t*_{1}*r*^{2}, *t*_{1}*r*^{3}, . . . , *t*_{1}*r ^{n}*

^{–1}=

*t*

_{n}The sum of the first *n* terms of a geometric series is given by the formula

If there is one term falling between two given terms of a geometric sequence it is called their *geometric mean.*

**EXAMPLES**

**1. (A) Find the seventh term of the geometric sequence 1, 2, 4, . . . , and****(B) the sum of the first seven terms.**

**(A)**

**(B)**

**2. The first term of a geometric sequence is 64, and the common ratio is** **.**

**For what value of n is**

**?**