Question

Enter the explicit rule for the geometric sequence. 120, 40, 403, 409, 4027, ...

a(n)=

Answer 1

Answer: 120(1/3)^n-1

Just took the test :)

Answer 2

The explicit rule is
`a_n=120((1)/(3))^(n-1)`.

The explicit rule is of the form

`a_n=a_1(r)^(n-1)`,
where a₁ is the first term and r is the common ratio (what we're multiplying by).

The first term of our sequence is 120.

The common ratio can be found by dividing a₂ by a₁:
40/120 = 1/3

We then plug those into our explicit rule.