Question

For the following geometric sequence find the explicit formula.
{12, -6, 3, ...}

Answer 1

Tn = 12(-1/2)^n

Explanation:

We have the nth term of a geometric sequence as

Tn = ar^n-1

a is the first term

r is the common ratio

n is term number

by dividing the second term by the first, we can have the common ratio

We have this as -6/12 or 3/-6 = -1/2

a the first term is 12

So we have the explicit formula as;

Tn = 12(-1/2)^n