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34   Chapter Onł


                          Powers of positive reals
                          For all positive real numberð x, and for all natural numberð n
                          where n   1, the following statementð are logically valid:

                                              0   x   1 → 0   x     (n 1)    x n

                                                                      n
                                                 x   1 → x  (n 1)    x   1
                                                                      n
                                                 x   1 → x  (n 1)    x   1


                          Even powers of negative reals
                          For all negative real numberð x, and for all even natural num-
                          berð n, the following statementð are logically valid:

                                                                       n
                                                x  è 1 → x   (n 2)    x   1
                                                                       n
                                                x   1 → x    (n 2)    x   1

                                              1   x   0 → 0   x      (n 2)    x n


                          Odd powers of negative reals
                          For all negative real numberð x, and for all odd natural numberð
                          n, the following statementð are logically valid:

                                                                      n
                                               x  è 1 → x   (n 2)    x  è 1
                                                                      n
                                               x   1 → x    (n 2)    x   1

                                              1   x   0 → 0   x      (n 2)    x n


                          Addition property
                          For all real numberð x, y, and z, the following statementð are
                          logically valid:

                                                 x   y → x   z   y   z


                                                 x   y → x   z   y   z
                                                 x   y → x   z   y   z


                                                 x   y → x   z   y   z
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