Determine whether or not each of the definition of ∗ given below gives a binary operation. In the event that ∗ is not a binary operation, give justification for this.
On Z+, define ∗ by a ∗ b = |a – b|
It is given On Z+, define ∗ by a ∗ b = | a – b|
We can see that for each a, b ϵ Z+, there is a unique element |a – b| in Z+.
⇒ * carries each pair (a, b) to a unique element a * b = |a – b| in Z+.
Therefore, * is a binary operation.