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WAEC Mathematics 1994 Question 20

Question 20

Graphs of Functions

Use the graph to answer this question. Which of the following equations can be solved by the points of intersection P and Q of the curve and the line PQ?

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

Answer: B (x2 − 4 = 0)

Explanation

The curve is y = x² + x + 1 and the line is y = x + 5. Where they meet, x² + x + 1 = x + 5, which simplifies to x² − 4 = 0.