passwella.
Menu

JAMB Mathematics 2001 Question 16

Question 16

Binary Operations

An operation is defined on the set of real numbers by a * b = a + b + 1. If the identity element is −1, find the inverse of the element 2 under *.

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

Answer: A (−4)

Explanation

The inverse b satisfies 2 * b = −1 (the identity). So 2 + b + 1 = −1, giving b = −4.