If R+ denotes the set of positive real numbers, then determine whether the binary structure(R+,.) is a group.
Solution. For each pair a,b in R+, the product ab is a unique positive real number. So R+, is closed under . , that is, . is a
Question Blank 1 of 4
operation on .
For all , we have so that is
Question Blank 2 of 4
on .
There exists such that for all . So,
Question Blank 3 of 4
is the identity element of under .
For each , there exists such that . So,
Question Blank 4 of 4
is the inverse of in under .
Hence is a group.