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WAEC Mathematics 2011 Question 29

Question 29

Graphs of Functions

The graph represents the relation y = x2 − 3x − 3. Find the values of x for which x2 − 3x = 7.

Diagram for this question
  1. A.−1.55, 4.55
  2. B.1.55, −4.55
  3. C.−1.55, −4.55
  4. D.1.55, 4.55
Show the answer and explanation

Answer: A (−1.55, 4.55)

Explanation

x2 − 3x = 7 means x2 − 3x − 3 = 4, so read where the curve meets y = 4: x ≈ −1.55 and 4.55 (exactly (3 ± √37)/2).