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WAEC Further Mathematics 2008 Question 17

Question 17

Binary Operations

A binary operation *, is defined on the set R, of real numbers by a * b = a2 + b + ab. Find the value of x for which 5 * x = 37.

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

Answer: B (2)

Explanation

5 * x = 25 + x + 5x = 25 + 6x. Setting 25 + 6x = 37 gives x = 2.