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JAMB Mathematics 1992 Question 15

Question 15

Polynomials

Resolve 3/(x2 + x − 2) into partial fractions

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

Answer: A (1/(x − 1) − 1/(x + 2))

Explanation

x2 + x − 2 = (x − 1)(x + 2). Writing 3 = a(x + 2) + b(x − 1): x = 1 gives a = 1 and x = −2 gives b = −1.