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GCE Mathematics 1990 Question 21

Question 21

Quadratic Equations

Solve the equation 7y2 = 3y.

  1. A.y = 3 or 7
  2. B.y = 0 or 7
  3. C.y = 0 or 3/7
  4. D.y = 0 or 9
  5. E.y = 0 or 10
Show the answer and explanation

Answer: C (y = 0 or 3/7)

Explanation

7y2 − 3y = 0 gives y(7y − 3) = 0, so y = 0 or y = 3/7.