Determine whether the following operation define a binary operation on the given set or not:(vii) ‘*’ on Q defined by a * b = (a – 1)/ (b + 1) for all a, b ∈ Q
Determine whether the following operation define a binary operation on the given set or not:(vii) ‘*’ on Q defined by a * b = (a – 1)/ (b + 1) for all a, b ∈ Q

(vii)Since, ‘*’ on Q defined by a * b = (a – 1)/ (b + 1) for all a, b ∈ Q

If a = 2 and b = -1 in Q,

    \[\begin{array}{*{35}{l}} a\text{ }*\text{ }b\text{ }=\text{ }\left( a\text{ }-\text{ }1 \right)/\text{ }\left( b\text{ }+\text{ }1 \right)  \\ =\text{ }\left( 2\text{ }-\text{ }1 \right)/\text{ }\left( -\text{ }1\text{ }+\text{ }1 \right)  \\ =\text{ }-1/0\text{ }\left[ which\text{ }is\text{ }not\text{ }defined \right]  \\ \end{array}\]

For a = 2 and b = -1

a * b does not belongs to Q

So, * is not a binary operation in Q.