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WAEC Mathematics 2005 Question 26

Question 26

Quadratic Equations

Given that one of the roots of the equation 2x2 + (k + 2)x + k = 0 is 2, find the value of k.

  1. A.−4
  2. B.−2
  3. C.−1
  4. D.−1/4
Show the answer and explanation

Answer: A (−4)

Explanation

Substitute x = 2: 8 + 2(k + 2) + k = 0, so 3k = −12 and k = −4.