An arithmetic sequence is a sequence in which each term after the first is obtained by adding a constant to the previous term. For example, 2, 5, 8, 11, 14 is an arithmetic sequence with five terms, in which the first term is 2 and the constant added is 3. Each row and each column in this array is an arithmetic sequence with five terms. What is the value of ?
A. 21B. 31C. 36D. 40E. 42
A. 21
B. 31
C. 36
D. 40
E. 42
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Worked solution
1. 2015 AMC 8 官方解析
第一项与第五项差 4 个公差,依次关系填出下表:第一行 ;第一列 ;第五列 。中间行首项 9、末项 53,故 。
Answer
B. 31
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