Question

A sequence is shown below. 4, 8, 16, 32, . . . Which formula can be used to determine the nth term in the sequence? Use the formula to find a8.

Answer 1

a8 = 512.

Explanation:

This is geometric sequence with common ratio r = 2 and first term a1 = 4.

nth term = a1 r^(n-1)

So a8 = 4 2(^8-1)

= 4 * 2^7

= 4*128 = 512.