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4 votes
Find the 9th term of the following geometric sequence: 1, –3, 9, –27. PLEASEEEEE HELP!!!!!!

A. –5,661
B. 7,241
C. –2,456
D. 6,561

User Bajaco
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8.1k points

1 Answer

2 votes
find common ratio
1 times -3=-3
-3 times -3=9

an=a1(r^(n-1))
a1=first term
r=common ratio
n=which term

an=1(-3)^(n-1)

9th term
n=9
an=1(-3)^(9-1)
an=1(-3)^(8)
an=1(6561)
an=6561


answer is D
User Alechan
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8.2k points