Exercise 3.2

Check the commutativity and associativity of each of the following binary operations: (xiii) ‘*’ on Q defined by a * b = (ab/4) for all a, b ∈ Q (xiv) ‘*’ on Z defined by a * b = a + b – ab for all a, b ∈ Z

(xiii) to check :commutativity of * \[\begin{array}{*{35}{l}} Let\text{ }a,\text{ }b\text{ }\in \text{ }Q,\text{ }then  \\ a\text{ }*\text{ }b\text{ }=\text{ }\left( ab/4 \right)  \\ =\text{ }\left(...

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