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WAEC Mathematics 1988 Question 19

Question 19

Quadratic Equations

Find the quadratic equation whose roots are x = −2 or x = 7

  1. A.x2 + 2x − 7 = 0
  2. B.x2 − 2x + 7 = 0
  3. C.x2 + 5x + 14 = 0
  4. D.x2 − 5x − 14 = 0
  5. E.x2 + 5x − 14 = 0.
Show the answer and explanation

Answer: D (x2 − 5x − 14 = 0)

Explanation

(x + 2)(x − 7) = 0 expands to x2 − 5x − 14 = 0.