Question

What are the first four terms of the geometric sequence with a t1 = 3 and tn = 2tn-1?

A 2, 18, 54, 68

B 3, 12, 24, 54

C 2, 6, 18, 54

D 3, 6, 12, 24

Answer 1

Taking the rule \(t_n=2t_{n-1}\), we can write the following for different value of \(n\), which may make understanding this clearer.\[t_2=2t_1\]\[t_3=2t_2\]\[t_4=2t_3\]Can you figure out what the terms of the sequence are using this derived information?

Answer 2

\[\Large t_n = 2*t_{n-1}\]
means that, to get a term of the sequence, you should multiply the PREVIOUS term by 2.
So to get the second term, multiply the first term by 2.
To get the third term, multiply the second term by 2.
To get the fourth term, multiply the third term by 2.

Answer 3

so its C?

Answer 4

Is that a guess?

Answer 5

NO

Answer 6

Okay, well I don't know how you got that answer, but it's not correct. Try again, and show me what you did.
The first term is given to you.
\[\large t_1 = 3\]

Answer 7

D