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JAMB Mathematics 1984 Question 23

Question 23

Quadratic Equations

The quadratic equation whose roots are 1 − √13 and 1 + √13 is

  1. A.x2 + (1 − √13)x + 1 + √13 = 0
  2. B.x2 + (1 + √13)x + 1 − √13 = 0
  3. C.x2 + 2x + 12 = 0
  4. D.x2 − 2x + 12 = 0
  5. E.x2 − 2x − 12 = 0.
Show the answer and explanation

Answer: E (x2 − 2x − 12 = 0.)

Explanation

The roots add to 2 and multiply to 1 − 13 = −12, so the equation is x² − 2x − 12 = 0.