RRB NTPC · Question 75
If a^2 + b^2 = 80 and a - b = 4, then ab = ? A. 20 B. 24 C. 28 D. 32
Show answer & explanation
Answer: (C) D
Explanation
(a − b)² = a² + b² − 2ab, so 16 = 80 − 2ab, 2ab = 64 and ab = 32.
Railways PYQCBT 1 2016
RRB NTPC · Question 75
Answer: (C) D
(a − b)² = a² + b² − 2ab, so 16 = 80 − 2ab, 2ab = 64 and ab = 32.