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WAEC Mathematics 2012 Question 45

Question 45

Graphs of Functions

The graph is that of y = 2x2 − 5x − 3. For what values of x will y be negative?

Diagram for this question
  1. A.−½ ≤ x < 3
  2. B.−½ < x ≤ 3
  3. C.−½ < x < 3
  4. D.−½ ≤ x ≤ 3
Show the answer and explanation

Answer: C (−½ < x < 3)

Explanation

y = (2x + 1)(x − 3) is zero at x = −½ and 3 and below the x-axis between them: −½ < x < 3.