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WAEC Mathematics 1991 (August) Question 8

Question 8

Quadratic Equations

Solve the equation: 3a + 10 = a2

  1. A.a = 5 or a = 2
  2. B.a = −5 or a = 2
  3. C.a = 10 or a = 0
  4. D.a = 5 or a = −2
  5. E.a = −5 or a = −2
Show the answer and explanation

Answer: D (a = 5 or a = −2)

Explanation

a2 − 3a − 10 = 0 gives (a − 5)(a + 2) = 0, so a = 5 or a = −2.