NextMockSearch exams, e.g. SSC CGL, UPPSC, Lekhpal
Railways PYQCBT 1 2020

RRB NTPC · Question 17

If \(\rm x^4 + \frac{1}{x^4} = 194\) find \(\rm x^3 + \frac{1}{x^3} \)

  1. 52

  2. 56

  3. 54

  4. 62

Show answer & explanation

Answer: (A) 52

Explanation

x⁴ + 1/x⁴ = 194 gives x² + 1/x² = √196 = 14, and x + 1/x = √16 = 4. Then x³ + 1/x³ = 4³ − 3 × 4 = 52.