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WAEC Mathematics 1998 Question 23

Question 23

Graphs of Functions

Use the graph to answer this question. The graph is that of the quadratic expression

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

Answer: C (y = x2 − x − 2)

Explanation

The curve crosses the x-axis at −1 and 2, so y = (x + 1)(x − 2) = x2 − x − 2 (it also passes through (0, −2)).