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WAEC Mathematics 2016 Question 11

Question 11

Algebraic Expressions

Find the values of y for which the expression (y2 − 9y + 18)/(y2 + 4y − 21) is undefined

  1. A.6, −7
  2. B.3, −6
  3. C.3, −7
  4. D.−3, −7
Show the answer and explanation

Answer: C (3, −7)

Explanation

It is undefined when the denominator is zero: y² + 4y − 21 = (y − 3)(y + 7) = 0, so y = 3 or −7.