Question

Find the formula an for the nth term of the geometric sequence satisfying the following conditions: a1 = -2,

and a = -486.

Answer 1

Explanation:

a1 = - 2

an = a1 * r^(n - 1)

a6 = -486

-486 = - 2 * r^(6-1) Divide by 2

243 = r^5

The largest value that r could be is 3.

4^5 = 1024

(243)^(1/5) = 3

So the general formula

an = -2*(3)^(n - 1)