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WAEC Further Mathematics 2014 Question 6

Question 6

Indices and Logarithms

If 8x ÷ (1/4)y = 1 and log2 (x − 2y) = 1, find the value of (x − y).

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

Answer: A (5/4)

Explanation

2^(3x) × 2^(2y) = 2⁰ gives 3x + 2y = 0; x − 2y = 2. Adding: 4x = 2, x = ½, y = −¾. x − y = 5/4.