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JAMB Mathematics 2002 Question 14

Question 14

Polynomials

Solve for x in the equation x3 − 5x2 − x + 5 = 0

  1. A.1, −1 or 5
  2. B.1, 1 or −5
  3. C.−1, 1 or −5
  4. D.1, 1 or 5
Show the answer and explanation

Answer: A (1, −1 or 5)

Explanation

Group the terms: x2(x − 5) − 1(x − 5) = (x − 5)(x − 1)(x + 1) = 0. So x = 1, −1 or 5.