AA
11-3 Geometric Sequences
Geometric Sequence:
* A sequence in which each term after
the first is found by multiplying a
constant r to the previous term.
Common Ratio:
* The constant r that you are multiplying by.
* Can find r by
term 2
term 4
=
term 1
term 3
nth Term of a Geometric Sequence:
* given by
an = (a1)(rn - 1)
where a1 is the first term and r is the
common ratio. n is any positive
integer.
n represents the term we are looking for.
1. Find the missing term in the geometric
sequence. 324, 108, 36, 12, ....
324, 108, 36, 12, ____,
Geometric Means:
* The terms between any two
nonsuccessive (not next to each other)
terms.
* Example: 2, ____, ____, ____, 162
(The spaces are the geometric means)
2. Find the sixth term of a geometric
sequence for which a = -3 and r = -2.
1
3. Write an equation for the nth term of the
geometric sequence 5, 10, 20, 40, ....
4. Find the seventh term of a geometric
sequence for which a3 = 96 and r = 2.
use n = 5, because from term 3 to
term 7 there are 5 terms.
11 - 3 Geometric Sequences
pg. 590 - 592
#1, 3, 14 - 16, 22, 23, 25, 28 - 30,
34, 35, 37, 38, 40, 41, 44, 45, 49,
50, 52 - 54, 57
(25 problems)
5. Find three geometric means between 3.12
and 49.92.