New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    Sum of squares of three consecutive numbers is 1589.

    Find the sum of first and third number.
    A 42 Correct Answer Incorrect Answer
    B 30 Correct Answer Incorrect Answer
    C 34 Correct Answer Incorrect Answer
    D 46 Correct Answer Incorrect Answer

    Solution

    Let the numbers be (x – 1), x and (x + 1) => (x – 1)2 + x2 + (x + 1)2 = 1589 => x2 – 2x + 1 + x2 + x2 + 2x + 1 = 1589 => 3x2 = 1589 - 2 => x2 = 1587/3 => x2 = 529 => x = 23 Required sum = (23 – 1) + (23 + 1) = 46

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