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WAEC Mathematics 2020 Question 22

Question 22

Quadratic Equations

A man is five times as old as his son. In four years time, the product of their ages would be 340. If the son's age is y, express the product of their ages in terms of y.

  1. A.5y2 − 16y − 380 = 0
  2. B.5y2 + 24y − 308 = 0
  3. C.5y2 − 16y − 330 = 0
  4. D.5y2 + 24y − 324 = 0
Show the answer and explanation

Answer: D (5y2 + 24y − 324 = 0)

Explanation

In four years the ages are 5y + 4 and y + 4. (5y + 4)(y + 4) = 5y2 + 24y + 16 = 340, so 5y2 + 24y − 324 = 0.