Which of the following statements is/are true: Let * be a binary operation on a non-empty set A such that a * b = a/b If A = Z then * is a binary operation on Z. If A = N then * is a binary operation on N.
Which of the following statements is/are true: Let * be a binary operation on a non-empty set A such that a * b = a/b If A = Z then * is a binary operation on Z. If A = N then * is a binary operation on N. Correct Answer Neither 1 nor 2
Concept:
An operation * on a non-empty set S, is said to be a binary operation if it satisfies the closure property.
Closure Property:
Let S be a non-empty set and a, b ∈ S, if a * b ∈ S for all a, b ∈ S then S is said to be closed with respect to operation *.
Calculation:
Given: * is a binary operation on a non-empty set A such that a * b = a/b
Statement 1: If A = Z then * is a binary operation on Z.
Let a = 1, b = 2 ∈ Z and operation * is defined above.
According to the definition of the operator, we have
⇒ a * b = 1/2
We know that, 1/2 is not an integer i.e a * b ∉ Z
So, Z is not closed with respect to the given operation *
Hence, statement 1 is false.
Statement 2: If A = N then * is a binary operation on N.
Let a = 1, b = 2 ∈ N and operation * is defined above.
According to the definition of the operator, we have
⇒ a * b = 1/2
We know that, 1/2 is not a natural number. i.e a * b ∉ N
So, N is not closed with respect to the given operation *
Hence, statement 2 is also false.
So, option D is the correct answer.