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WAEC Further Mathematics 2011 Question 1

Question 1

Binary Operations

A binary operation * is defined on the set of real numbers, R, by a * b = a + b − 1. Find the identity element under the operation *.

  1. A.−1
  2. B.0
  3. C.1
  4. D.2
Show the answer and explanation

Answer: C (1)

Explanation

If e is the identity, a * e = a + e − 1 = a, so e − 1 = 0 and e = 1.