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WAEC Further Mathematics 2020 Question 11

Question 11

Functions

Given that f(x) = 2x and g(x) = 3x2, find the values of x for which f−1(x) = g(x).

  1. A.x = 0 or x = 1/6
  2. B.x = 0 or x = 2/3
  3. C.x = 2/3 or x = 1/12
  4. D.x = 1/6 or x = 2/3
Show the answer and explanation

Answer: A (x = 0 or x = 1/6)

Explanation

f⁻¹(x) = x/2. x/2 = 3x² gives x(6x − 1) = 0, so x = 0 or 1/6.