Question

What is the recursive formula for this geometric sequence? -3, -21, -147, -1029, ...

Answer 1

Answer:

an = an-1 *7

a1 = -3

Step-by-step explanation:

We are multiplying by 7 each time

-3*7 = -21

-21 *7 = -147

The formula for a geometric sequence is

an = a1 * (r)^(n-1)  where r is the common ratio and n is the term number

an = -3 ( 7) ^(n-1)

The recursive formula is

an = an-1 * r

an = an-1 *7

a1 = -3

Answer 2

Answer:

Step-by-step explanation:

common ratio = 7

nth term = ((n-1)th term)×7 = a₁×7ⁿ⁻¹