How do you find a_9a9 when a_1 = 1000, r = 1/3?a1=1000,r=13?

1 Answer
Jim G.
May 25, 2016

a_9=1000/6561a9=10006561

Explanation:

For the standard geometric sequence.

a,ar,ar^2,ar^3,..............,ar^(n-1)

where a is 1st term

r ,the common ratio =a_2/a_1=a_3/a_2=....=a_n/a_(n-1)

and the nth term a_n=ar^(n-1)

here n = 9 , a = 1000 and r=1/3

rArra_9=1000(1/3)^8=1000/3^8=1000/6561

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