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WAEC Further Mathematics 2018 Question 40

Question 40

Functions

Two functions f and g are defined on the set of real numbers by f: x → x2 + 1 and g: x → x − 2. Find f o g.

  1. A.x2 + 4x − 5
  2. B.x2 − 4x + 5
  3. C.x2 − 1
  4. D.x − 1
Show the answer and explanation

Answer: B (x2 − 4x + 5)

Explanation

f(g(x)) = (x − 2)² + 1 = x² − 4x + 5.