New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

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

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