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

    Question

    If (x + 1/x) = 5, then value of x3 +

    1/x3 is:
    A 110 Correct Answer Incorrect Answer
    B 125 Correct Answer Incorrect Answer
    C 140 Correct Answer Incorrect Answer
    D 135 Correct Answer Incorrect Answer

    Solution

    (x + 1/x) = 5 On cubing both sides: x3 + 1/x3 + 3*x*1/x(x + 1/x) = 125 ⇒ x3 + 1/x3 = 125 – 3*5 = 110

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