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    Question

    The sum of the first 10 terms of an arithmetic sequence

    is 60 and the 10th term is 5. What is the first term of the sequence?
    A 7 Correct Answer Incorrect Answer
    B 8 Correct Answer Incorrect Answer
    C 9 Correct Answer Incorrect Answer
    D 6 Correct Answer Incorrect Answer

    Solution

    Sn = (n/2) [2a + (n - 1)d] 60 = 10/2 [2a + (10 - 1)d] 60 = 5 [2a + 9d] 2a + 9d = 12 ------ (i) Given 10th term is 5, so => a10 = a + 9d => a + 9d = 5 ------ (ii) Solving eqn (i) and (ii) we get, => a = 7

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