If , then .

Let and .

Case(i):

                       (Expression)

                  (Substitute and )

                        (Add left side terms)

                                    (Multiply)

                                        (Simplify)

The stament is true.

Case(ii):

         (Expression)

      (Substitute and )

                       (Add right side terms)

                                (Multiply)

                                      (Simplify)

The stament is false.

The counterexample is and ,then .

The counterexample is and ,then .