# Q- Let S be a set on which an associative binary operation · has been defined such that S contains an identity element eS. Let U(S) be the set of all the units in S. Prove that U(S) is a group with respect to the operation ·. It is called the group of units of S.

Question

Q- Let S be a set on which an associative binary operation · has been defined such that S contains an identity element eS. Let U(S) be the set of all the units in S. Prove that U(S) is a group with respect to the operation ·. It is called the group of units of S.