How do you find the nth term rule for $12,4,4/3,4/9,...$ ?

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Answer 1 · 2016-07-18T10:14:46

$T_n = 12 xx (1/3)^(n-1)$

This is a GP which first term , a, of 12 and the common ratio ,r,of 3.
The common ratio is found from dividing any two consecutive terms..

$r = T_2/T_1 = 4/12 = 1/3$

The general term for any GP is $T_n=- ar^(n-1)$

Substituting the values for a and r we get..

$T_n = 12 xx (1/3)^(n-1)$

How do you find the nth term rule for 12,4,4/3,4/9,...12,4,4/3,4/9,...?