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WAEC Mathematics 2020 Question 48

Question 48

Graphs of Functions

The graphs of the equations y = 2x + 5 and y = 2x2 + x − 1 are shown. Find the points of intersection of the two graphs.

Diagram for this question
  1. A.(2.0, 9.0) and (−1.5, 2.0)
  2. B.(2.0, 8.5) and (−1.5, 2.0)
  3. C.(2.0, 8.0) and (−1.5, 2.5)
  4. D.(2.0, 7.5) and (−1.5, 2.5)
Show the answer and explanation

Answer: A ((2.0, 9.0) and (−1.5, 2.0))

Explanation

Set 2x2 + x − 1 = 2x + 5: 2x2 − x − 6 = 0, (2x + 3)(x − 2) = 0. x = 2 gives y = 9 and x = −1.5 gives y = 2.