Subject

    Quantitative Aptitude

    Topic

    Number

    The sum of the squares of three numbers is 138, while the sum of their products taken two at a time is Their sum is:

    ক)
    20
    খ)
    30
    গ)
    40
    ঘ)
    None of these

    Explanation

    Let the numbers be a, b and c. Then, a2 + b2 + c2 = 138 and (ab + bc + ca) = 131. (a + b + c)2 = a2 + b2 + c2 + 2(ab + bc + ca) = 138 + 2 x 131 = 400. => (a + b + c) = √400 = 20.

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