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WAEC Mathematics 2015 Question 11

Question 11

Quadratic Equations

Adding 42 to a given positive number gives the same result as squaring the number. Find the number.

  1. A.14
  2. B.13
  3. C.7
  4. D.6
Show the answer and explanation

Answer: C (7)

Explanation

x² = x + 42 gives (x − 7)(x + 6) = 0; the positive number is 7.