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Railways PYQCBT 1 2016

RRB NTPC · Question 81

If a - b = 5 and a^2 + b^2 = 31 then find the value of ab? A. 4 B. 5 C. 2 D. 3

  1. C

  2. A

  3. B

  4. D

Show answer & explanation

Answer: (D) D

Explanation

(a − b)² = a² + b² − 2ab gives 25 = 31 − 2ab, so 2ab = 6 and ab = 3.