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WAEC Further Mathematics 2017 Question 27

Question 27

Polynomials

A curve is given by y = 5 − x − 2x2. Find the equation of its line of symmetry.

  1. A.x = −41/8
  2. B.x = −1/4
  3. C.x = 1/4
  4. D.x = 41/8
Show the answer and explanation

Answer: B (x = −1/4)

Explanation

The axis of symmetry passes through the turning point: dy/dx = −1 − 4x = 0, so x = −1/4.