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WAEC Mathematics 1991 (August) Question 4

Question 4

Algebraic Expressions

For what value of y is the expression (y + 2)/(y2 − 3y − 10) undefined?

  1. A.y = 0
  2. B.y = 2
  3. C.y = 3
  4. D.y = 5
  5. E.y = 10
Show the answer and explanation

Answer: D (y = 5)

Explanation

It is undefined when the denominator is zero: y2 − 3y − 10 = (y − 5)(y + 2) = 0, so y = 5 or y = −2; only y = 5 is offered.