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WAEC Mathematics 1992 Question 12

Question 12

Quadratic Equations

What must be added to the expression x2 − 18x to make it a perfect square?

  1. A.3
  2. B.9
  3. C.36
  4. D.72
  5. E.81
Show the answer and explanation

Answer: E (81)

Explanation

Add the square of half the coefficient of x: (18/2)2 = 81, giving (x − 9)2.