Hi, I have some troubles with this question. Define an operator * on [tex]R[/tex] by [tex]x*y = 2xy -x -y +1[/tex] a) is * commutative? b) is * associative? I can easily see that * is commutative, but how do i test for associativity? The rule states that (x*y)*z = x*(y*z) But what is z ?