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JAMB Mathematics 1986 Question 28

Question 28

Indices

Find the values of x which satisfy the equation 16x − 5 × 4x + 4 = 0

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

Answer: C (0 and 1)

Explanation

Put y = 4ˣ: y² − 5y + 4 = 0, so y = 1 or 4. Then 4ˣ = 1 gives x = 0 and 4ˣ = 4 gives x = 1.