Question

    Find the value of (21)³ + (- 12) ³ + ( - 9)³.

    A 6938 Correct Answer Incorrect Answer
    B 6304 Correct Answer Incorrect Answer
    C 6774 Correct Answer Incorrect Answer
    D 6804 Correct Answer Incorrect Answer

    Solution

    (a 3  + b 3  + c 3 ) = 3abc, if (a + b + c) = 0

    Here, 21 + ( - 12) + ( - 9) = 21 - 21 = 0

    So, (21)  3  + ( - 12)  3  + ( - 9)  3  = 3 X 21 X ( - 12) X ( - 9) = 6,804

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