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Use geometric mean to find the 7th term in a geometric sequence if the 6th term is 12 and the 8th term is 27

User Gleb Esman
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1 Answer

2 votes

Answer:

18

Explanation:

First, use the equation for geometric mean; an=a1r^n-1

*where is an is the number at an n term, r is the ratio and a1 is the first number of the sequence.*

12 = a1 r^5

27 = a1r^7

From the equations above,

a1 = 128/81

r = 3/2

Therefore, the 7th term is:

an = (128/81) (3/2)^6

an = 18

hope this helps :)

User Daniel Rosenwasser
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