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WAEC Further Mathematics 2024 Question 11

Question 11

Indices and Logarithms

Solve: 22x − 5(2x) + 4 = 0.

  1. A.x = 0 and 2
  2. B.x = 1 and 2
  3. C.x = 0 and 1
  4. D.x = 2 and 4
Show the answer and explanation

Answer: A (x = 0 and 2)

Explanation

Let p = 2ˣ: p² − 5p + 4 = 0, (p − 1)(p − 4) = 0. 2ˣ = 1 gives x = 0 and 2ˣ = 4 gives x = 2.