Question 6. Let ∗ be the binary operation on N given by a ∗ b = L.C.M. of a and b. Find
(v) Which elements of N are invertible for the operation ∗?
An element a is invertible in N
if
Here a is inverse of b.
a*b=1=b*a
a*b=L.C.M. od a and b
a=b=1
So 1 is the only invertible element of N