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WAEC Mathematics 2012 Question 46

Question 46

Differentiation

The graph is that of y = 2x2 − 5x − 3. What is the gradient of y = 2x2 − 5x − 3 at the point x = 4?

Diagram for this question
  1. A.11.1
  2. B.10.5
  3. C.10.3
  4. D.9.9
Show the answer and explanation

Answer: A (11.1)

Explanation

The gradient is dy/dx = 4x − 5, which is 11 at x = 4. (A tangent drawn on the graph gives about 11.)