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WAEC Further Mathematics 2013 Question 13

Question 13

Polynomials

Find the range of values of x for which x2 + 4x + 5 is less than 3x2 − x + 2.

  1. A.x > −½, x > 3
  2. B.x < −½, x > 3
  3. C.−½ ≤ x ≤ 3
  4. D.−½ < x < 3
Show the answer and explanation

Answer: B (x < −½, x > 3)

Explanation

We need 2x² − 5x − 3 > 0, i.e. (2x + 1)(x − 3) > 0, so x < −½ or x > 3.