MÌNH LÀM CÂU 2 THÔI NHÉ

                                  9^2X:9=729

                                     9^2X=729:9

                                      9^2X=81

                                       9^2X=9²

              SUY RA;         2.X=2

                                       X=2:2

                                       X=1

Vậy x=1