Question

Which of the following recursive formulas represents the same geometric sequence as the formula an = 2 • 3n - 1?

A. an = 3 • an - 1
B. an = 2 • an - 1
C. an = 3 + an - 1
D. an = 6 • an - 1

Answer 1

geometric, so that (n - 1) is all exponent i assume

Answer 2

\[\large a _{n}=2*(3)^{n-1}\]

Answer 3

Dan did well to ask if his interpretation of your "n-1" is correct or not. Please, if you write this again, enclose the "n-1" inside parentheses to emphasize that the entire "n-1" is your exponent.

Answer 4

i just know this becuase everyone does that, prolly a copy paste thing , idk

Answer 5

Let n = 1, 2, 3, 4, etc. and calculate the corresponding terms of this geom. series.

Next, using these known values of the geom. sequence, check out each of the four possible answers.

Answer 6

@lilkg77: Time for you to get involved. Questions? Proposals?

Answer 7

look at what the geometric series does

the start value is 2, each time n increases, a 3 is multiplied on

for increasing values of n...

2*3
2*3*3
2*3*3*3
....

it takes the last value and multiplies it by 3

Answer 8

@lilkg77: Your input, please?

Answer 9

Dan: Please wait for lilkg77 to say something. Thx.

Answer 10

the recursive way to say this, if you write a1, then a2 in terms of a1, then a3 in terms of a2, , you see a pattern for the nth term an

Answer 11

the second term is 3 times the first
the third term is 3 times the second
the 4th term is 3 times the 3rd

......
that is the recurrsion pattern, what can you say in general for the nth term from that

Answer 12

@danjs: Please do not continue explaining and explaining when there is no involvement at all on the part of the person asking the question.