Question

The first term of a geometric sequence is −2 and the common ratio is 3. What is the fourth term of the sequence?

Answer 1

Explanation:

The formula for a geometric sequence is

`a_n=a_1*r^(n-1)` where n is the position in the sequence, a1 is the first number in the sequence, and r is the common ratio. For us, a1 = -2 and r = 3, n = the 4th term:

`a_4=-2*3^(4-1)` and

`a_4=-2*3^3` and

`a_4=-2*27` so

`a_4=-54`

The 4th term in the geometric sequence is -54.