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Railways PYQCBT 1 2020

RRB NTPC · Question 21

If x satisfies the equation x^2 - 2x + 1 = 0, then the value of \(\rm x^3 - \frac{1}{x^3}\) is:

  1. 1/3

  2. 1

  3. -1

  4. 0

Show answer & explanation

Answer: (D) 0

Explanation

x² − 2x + 1 = (x − 1)² = 0, so x = 1. Then x³ − 1/x³ = 1 − 1 = 0.