Answer:
The formula which can be used to describe the sequence is:
⇒ 3rd answer
Step-by-step explanation:
The terms of the sequence are -81, 108, -144, 192, ...
∵ 108 ÷ -81 =
∵ -144 ÷ 108 =
∵ 192 ÷ -144 =
- There is a constant ratio between each two consecutive terms
∴ The sequence is a geometric sequence
The formula of the nth term of the geometric sequence is , where a is the first term and r is the constant ratio between each two consecutive terms
∵ The first term is -81
∴ a = -81
∵ The constant ratio =
∴ r =
- Substitute then in the formula above
∴
Assume that = f(x)
∴ n = x
∴
The formula which can be used to describe the sequence is: