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JAMB Mathematics 2006 Question 37

Question 37

Binary Operations

A binary operation ⊖ defined on the set of real numbers is such that x⊖y = xy/6 for all x, y ∈ R. Find the inverse of 20 under this operation when the identity element is 6.

  1. A.1/12
  2. B.10/3
  3. C.1/20
  4. D.9/5
Show the answer and explanation

Answer: D (9/5)

Explanation

20 ⊖ x = 20x/6 must equal the identity 6, so 20x = 36 and x = 9/5.