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JAMB Mathematics 1993 Question 4

Question 4

Indices

Solve for y in the equation
10y × 5(2y − 2) × 4(y − 1) = 1

  1. A.¾
  2. B.⅔
  3. C.1
  4. D.5/4
Show the answer and explanation

Answer: B (⅔)

Explanation

Write everything in powers of 2 and 5: 2y·5y × 52y−2 × 22y−2 = 103y−2. This equals 1 = 100, so 3y − 2 = 0 and y = ⅔.