Question

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

Answer 1

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 :)