In an arithmetic sequence the third term is 6 and the seventh term is -2. What is the 9th term?
Answer and explanation
Correct answer: C. -6
- Step 1: Seventh term - third term = 4d, so 4d = -2 - 6 = -8 and d = -2. Step 2. First term a = 6 - 2 x -2 = 10. Step 3. a_9 = 10 + 8 x -2 = -6. Answer: -6. Why not the others: -8: That is the next term, the 10th. -4: That is the previous term, the 8th. 12: That adds 1 for each step instead of the common difference.
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