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Railways PYQCBT 1 2016

RRB NTPC · Question 66

If 19x^2 = 100^2– 90^2, then find the value of x. A. 10 B. 9 C. 11 D. 12

  1. C

  2. A

  3. D

  4. B

Show answer & explanation

Answer: (B) A

Explanation

100² − 90² = (100 − 90)(100 + 90) = 10 × 190 = 1900. So 19x² = 1900, x² = 100 and x = 10.