Subject

    Quantitative Aptitude

    Topic

    Algebra

    Find the largest positive integer n such that n3+ 100, is divisible by n + 10.

    ক)
    890
    খ)
    920
    গ)
    990
    ঘ)
    940
    ঙ)
    None of these

    Explanation

    We know that, a 3 + b 3 = (a + b) (a 2 –ab + b 2 ) ∴ n 3 + 10 3 = n 3 + 1000 = (n + 10) (n 2 – 10n + 100) Thus, (n + 10) divides (n 3 + 1000). Given equation, n 3 + 100 = (n 3 + 1000) – 900 Since, (n + 10) divides (n 3 + 100) and (n 3 + 1000), it must divide 900 also. So, largest value of (n + 10) = 900 ∴ n = 890

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