If x – 1/x=2, Then the Value of x³ – 1/x³ is :

  1. 11
  2. 15
  3. 2
  4. 14
Anurag Mishra Professor Asked on 17th November 2015 in Maths.
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  • 1 Answer(s)

    Answer: (4) 14 

    Explanation:-

    X – 1/X = 2       …………………….. (1)
    Cube on both side,
    (X – 1/X)³ = 2³
    X³ – (1/X)³ – 3 X x 1/X (X – 1/X) = 2 x 2 x 2
    X³ – 1/X³ – 3 x 2 = 8
    X³ – 1/X³ – 6 = 8
    X³ – 1/X³ = 8 + 6
    X³ – 1/X³ = 14

    Hence, the answer is (4) 14.

    Anurag Mishra Professor Answered on 17th November 2015.
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