Question

Find the first term of the following geometric sequence.

_____, 39, 117, 351, 1,053, ...

Answer 1

Since it is a geometric sequence, there has to be a common ratio between the terms. Divide a term by the previous term to figure out what it is.

Answer 2

So:
\[\frac{117}{39} = 3\]
the ratio is 3, so divide 39 by 3 to get your answer :)

Answer 3

but the appex thing said the answer is 13

Answer 4

yeah, (39/3) = 13 :)

Answer 5

39/3 = 13 right?

Answer 6

divide 117/39 =3 thus 3 is the common ratio \[T_{n}=ar ^{n-1}\]

Answer 7

ok, i c

Answer 8

n=1
r=3
use the above formula to look 4 a