2009 AMC 12A Problem 7
Attempt Problem 7 of the 2009 AMC 12A below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2009 AMC 12A solutions, or check the answer key.
All problems are used with official legal permission of the Mathematical Association of America (MAA).
7.
The first three terms of an arithmetic sequence are and respectively. The th term of the sequence is What is
Answer: B
Small hint:
Consecutive differences are equal:
Big hint:
Solve for then find the first term and common difference
Solution:
Equal consecutive differences give that is so
The first three terms are with common difference
The th term satisfies so and
Thus, the correct answer is B.
Problem 7 in other years
- 1950 AMC 12
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