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WAEC Further Mathematics 2014 Question 4

Question 4

Binary Operations

Given that x * y = (x + y)/2, x o y = x2/y and (3 * b) o 48 = 1/3, find b, where b > 0.

  1. A.8
  2. B.6
  3. C.5
  4. D.4
Show the answer and explanation

Answer: C (5)

Explanation

3 * b = (3 + b)/2. Then ((3 + b)/2)² ÷ 48 = 1/3, so ((3 + b)/2)² = 16, (3 + b)/2 = 4 and b = 5.