- A
- B
- C
- D
Step-by-Step Solution
S₇ = gives , and S₁₇ = gives . Subtracting, , so and . Then Sₙ = .
Answer: C)
In an arithmetic progression the sum of the first 7 terms is 49 and the sum of the first 17 terms is 289. The sum of its first n terms is:
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