Question

The first four terms of a geometric sequence are 2, 6, 18 and 54.
What is the 8th term?

Answer 1

4374

Explanation:

First term, a =2

Common ratio, r = 3

nth term = a.r^(n-1)

where , n is the number of terms

8th term = 2.(3)^(8–1)

=2(2187)

=4374

⇒ A geometric progression, sometimes termed a geometric sequence, is a series of integers in which each term after the first is determined by multiplying the preceding one by a fixed, non-zero value known as the common ratio.

Answer 2

4374

Explanation:

We are multiplying by 3 each time

2*3 = 6

6*3 =18

18*3 = 54

The formula is

an = 2 * 3^(n-1) where n is the term number

a8 = 2 * 3^(8-1)

a8 = 2 * 3^7

a8 = 2*2187

a8 = 4374