Question

A geometric sequence has the explicit formula an = (-2) x 3^n- 1. What is the 4th term?

Answer 1

-54

Explanation:

Please write this sequence in the following form: a(n) = (-2)*3^(n- 1)

Then a(1) = -2*3^0 = -2

a(2) = -2*3^(2 - 1) = -6

a(3) = -2*3^(3 - 1) = -2*9 = -18

a(4) = -2*3^(4-1) = -2*27 = -54