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WAEC Mathematics 2020 Question 49

Question 49

Graphs of Functions

The graphs of the equations y = 2x + 5 and y = 2x2 + x − 1 are shown. If x = −2.5, what is the value of y on the curve?

Diagram for this question
  1. A.y = 8.0
  2. B.y = 8.5
  3. C.y = 9.0
  4. D.y = 9.5
Show the answer and explanation

Answer: C (y = 9.0)

Explanation

On the curve y = 2(−2.5)2 + (−2.5) − 1 = 12.5 − 3.5 = 9.0.