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    Question

    If (x – (1/x) = 5√2), then calculate the value of

    {(x4 + (1/x4)} ÷ 1351}.
    A 2 Correct Answer Incorrect Answer
    B -2 Correct Answer Incorrect Answer
    C 3 Correct Answer Incorrect Answer
    D -1 Correct Answer Incorrect Answer

    Solution

    x – 1/x = 5√2

    On squaring both sides, we get

    (x – 1/x )2 = (5√2)2

    Or, x2 + 1/x2 - 2 = 25 X 2

    Or, x2 + 1/ x2 = 50 + 2

    Or, x2 + 1/x2 = 52

    On squaring both sides again, we get

    x4 + 1/ x4 + 2 = 2704

    Or, x4 + 1/ x4 = 2702

    So, (x4 + 1/ x4) ÷ 1351= 2702 ÷ 1351 = 2

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