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WAEC Further Mathematics 2020 Question 29

Question 29

Differentiation

In what interval is the function f: x → 2x − x2 increasing?

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

Answer: B (x < 1)

Explanation

f′(x) = 2 − 2x is positive when x < 1, so f is increasing for x < 1.