Question

What is the explicit formula for the geometric sequence with this recursive formula? a1=-7

Answer 1

ANSWER

D. $a_n= - 7( \frac{1}{3} )^{n - 1}$

EXPLANATION

The given explicit formula is

$a_1= - 7$

and

$a_n=\frac{1}{3} a_{n-1}$

This implies that,

$r = \frac{1}{3}$

The explicit formula is given by:

$a_n=a_{1}( \frac{1}{3} )^{n - 1}$

We substitute the known values to get;

$a_n= - 7( \frac{1}{3} )^{n - 1}$