Question

Write the explicit formula for the geometric sequence. Then find the fifth term in the sequence.

a1 = –4, a2 = 8, a3 = –16

Answer 1

B. an = –4 · (–2)n–1; –64

Explanation:

Answer 2

The sequence: a 1 = - 4, a 2 = 8, a 3 = -16,...
a 2 = a 1 * r
8 = - 4 * r
r = 8 : ( - 4 )
r = - 2
a n = a 1 * r^(n-1)
a 5 = - 4 * ( - 2 ) ^4 = - 4 * 16 = - 64
Answer:
The fifth term in the sequence is - 64.