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WAEC Further Mathematics 2022 Question 19

Question 19

Indices and Logarithms

Solve: 32x−2 − 28(3x−2) + 3 = 0.

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

Answer: D (x = 0 or x = 3)

Explanation

Let p = 3ˣ: p²/9 − 28p/9 + 3 = 0, so p² − 28p + 27 = 0, (p − 1)(p − 27) = 0. 3ˣ = 1 or 27 gives x = 0 or 3.