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JAMB Mathematics 1990 Question 20

Question 20

Quadratic Equations

What must be added to 4x2 − 4 to make it a perfect square?

  1. A.−1/x2
  2. B.1/x2
  3. C.1
  4. D.−1
Show the answer and explanation

Answer: B (1/x2)

Explanation

(2x − 1/x)2 = 4x2 − 4 + 1/x2. So adding 1/x2 to 4x2 − 4 makes a perfect square.