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    Question

    For what value of a does the quadratic equation x² + ax +

    81 = 0 have real and identical roots?
    A 11 Correct Answer Incorrect Answer
    B Both 18 and -18 Correct Answer Incorrect Answer
    C 19 Correct Answer Incorrect Answer
    D 27 Correct Answer Incorrect Answer

    Solution

    ATQ,
    Discriminant should be zero:

    a² - 4×1×81 = 0

    ⇒ a² = 324

    ⇒ a = ±18

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