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QuestionMathematics

What is the recursive formula for this geometric sequence? $- 4,- 24,- 144,- 864, \ldots$ O A. $\left\{\begin{array}{l}a_{1}=- 4 \\ a_{n}=a_{n- 1} \bullet 6\end{array}\right.$ O B. $\left\{\begin{array}{l}a_{1}=- 6 \\ a_{n}=a_{n- 1} \bullet 30\end{array}\right.$ O C. $\left\{\begin{array}{l}a_{1}=- 4 \\ a_{n}=a_{n- 1} \bullet 30\end{array}\right.$ O D. $\left\{\begin{array}{l}a_{1}=- 6 \\ a_{n}=a_{n- 1} \bullet 4\end{array}\right.$
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Answer

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Step 1:
Let's solve this step by step:

Step 2:
: Identify the first term and the common ratio

\frac{-864}{-144} = 6
- Let's find the common ratio by dividing consecutive terms:

Step 3:
: Verify the pattern

- Fourth term: $$-144 \times 6 = -864
- Second term: - 4 \times 6 = - 24

Step 4:
: Construct the recursive formula

- First term: $$a_{1} = -4
- Recursive rule: a_{n} = a_{n- 1} \times 6

Step 5:
: Match with given options

- This matches option A: $$\left\{\begin{array}{l}a_{1}=-4 \ a_{n}=a_{n-1} \bullet 6\end{array}\right.

Final Answer

Option A is the correct recursive formula for this geometric sequence.