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JAMB Mathematics 1990 Question 14

Question 14

Algebraic Expressions

Express r in terms of p and q in the following equation: p/√2 = √(r/(r + q))

  1. A.r = p2q/(2 − p2)
  2. B.r = pq2/(2 − q2)
  3. C.r = p2q2/(2 − pq)
  4. D.r = p/(q(2 − p))
Show the answer and explanation

Answer: A (r = p2q/(2 − p2))

Explanation

Square both sides: p2/2 = r/(r + q), so p2r + p2q = 2r. Then r(2 − p2) = p2q, giving r = p2q/(2 − p2).