Let ∗ be the binary operation on N given by a∗b=LCM of a and b.
(i) Is ∗ associative?
The binary operation ∗ on N is defined as a∗b=LCM of a and b.
For a,b,c∈N, we have
(a∗b)∗c =(LCM of a and b) ∗c = LCM of a,b, and c
a∗(b∗c)=a∗(LCM of b and c) = LCM of a,b and c
a∗(b∗c)=a∗(b∗c). Thus, the operation ∗ is associative.