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    Question

    Suppose [a + (1/16a)] = 3, then the value of [16a³ +

    (1/256a³)] is:
    A 470 Correct Answer Incorrect Answer
    B 522 Correct Answer Incorrect Answer
    C 423 Correct Answer Incorrect Answer
    D 327 Correct Answer Incorrect Answer

    Solution

    ATQ,

    If a + 1/16a = 3

    Cubing both sides, we get;

    So, a³ + 1/4096a³ + 3 × a × 1/16a × 3 = 27

    Or, a³ + 1/4096a³ = 27 – 9/16 = 423/16

    Multiplying both sides by 16, we get;

    16a³ + 1/256a³ = 423

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