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JAMB Mathematics 1985 Question 22

Question 22

Quadratic Equations

Solve the following equation 2/(2r − 1) − 5/3 = 1/(r + 2)

  1. A.(−1, 5/2)
  2. B.(1, −5/2)
  3. C.(5/2, 1)
  4. D.(2, 1)
  5. E.(1, 2).
Show the answer and explanation

Answer: B ((1, −5/2))

Explanation

2/(2r − 1) − 1/(r + 2) = 5/((2r − 1)(r + 2)) = 5/3, so (2r − 1)(r + 2) = 3, i.e. 2r² + 3r − 5 = 0. Then (r − 1)(2r + 5) = 0 and r = 1 or −5/2.