Question

The nth term of a geometric sequence is a sub n =a sub 1 times r ^n-1 , where a sub 1 is the first term and r is the common ratio. Identify a sub 1 and r for each geometric sequence.

Answer 1

Answer/Step-by-step explanation:

Common ratio of a sequence can be gotten by dividing any of the consecutive term in a sequence, by the term before it.

Thus,

For the sequence, $3, 9, 27. . .$ : $a_1 = 3$

$r = \frac{9}{3} = 3$

For the sequence, $8, 4, 2, 1. . .$ : $a_1 = 8$

$r = \frac{4}{8} = \frac{1}{2}$

For the sequence, $-16, 64, -256 . .$ : $a_1 = -16$

$r = \frac{64}{-16} = -4$