If a - b = 3 and a2 + b2 = 29, find the value of ab.
Correct answer: A. 10
- A. 10
- B. 12
- C. 15
- D. Both A and B
Explanation
Solve using substitution A - B = 3. A = 3+B. We know that, A2+ B2 = 29. (3+B) 2+ B2 = 29. 9+B2+ 6B + B2 = 29. 2B2+ 6B - 20 = 0. B2+ 3B - 10 = 0. B = 2 and B = -5. then take+ valve B = 2. We know that A - B = 3. Hence A - 2 = 3. A = 5. AB = 2*5 = 10.
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