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WAEC Mathematics 2013 Question 33

Question 33

Variation

If y varies directly as the square root of (x + 1) and y = 6 when x = 3, find x when y = 9.

  1. A.8
  2. B.7
  3. C.6
  4. D.5
Show the answer and explanation

Answer: A (8)

Explanation

y = k√(x + 1): 6 = 2k, so k = 3. 9 = 3√(x + 1) gives x + 1 = 9 and x = 8.