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WAEC Mathematics 2006 Question 30

Question 30

Graphs of Functions

Use the graphs to answer this question. Which of these equations best describes the points of intersection of the curve and the line?

Diagram for this question
  1. A.x2 + 5x − 6 = 0
  2. B.x2 − 5x − 6 = 0
  3. C.x2 + x − 6 = 0
  4. D.x2 − x − 6 = 0
Show the answer and explanation

Answer: C (x2 + x − 6 = 0)

Explanation

The curve and the line meet at x = −3 and x = 2, so the equation is (x + 3)(x − 2) = 0, i.e. x2 + x − 6 = 0. (Line y = −x − 3 and curve y = 3 − 2x − x2 give the same equation.)