Question

What is the first term of the geometric sequence presented in the table below?

Answer 1

Fron the table given:

A3 = 112,
A8 = - 3,584

An = A1 *r ^ (n-1)

=> A3 = A1 (r^2) = 112

A8 = A1(r^7) = - 3,584

=> - 3584 / 112 = (r^7) / (r^2)

=> (r^5) = - 32

=> r = - 2

=> A1 (- 2)^2 = 112

=> A1 = 112 / 4 = 28

Answer: a1 = 28