A is the set of all the numbers on which a function is defined. It may be real as well.
Let S be the set of all rational numbers except 1 and * be defined on S by a * b = a + b - ab, for all a, b ∈ S. Prove that: (i) * is a binary operation on S (ii) * is commutative as well as associative. [CBSE 2014]