Find the sum of a geometric series

1
EXAMPLE 5
Find the sum of a geometric series
a1 4(3)1 1 4
Identify first term.
r 3
Identify common ratio.
Write rule for S16.
Substitute 4 for a1 and 3 for r.
86,093,440
Simplify.
2
EXAMPLE 6
Use a geometric sequence and series in real life
3
EXAMPLE 6
Use a geometric sequence and series in real life
SOLUTION
an 5.02(1.059)n 1
Write a rule for an.
4
for Examples 5 and 6
GUIDED PRACTICE
7. Find the sum of the geometric series
6( 2)i1.
8. MOVIE REVENUE Use the rule in part (a) of
Example 6 to estimate the total box office
revenue at U.S. movie theaters in 2000.