bonjour,
sujet: Résoudre les systèmes 1) 5x+2y=-3
                                                    -3x-y=1

                                                2) 2(x-1)=3y-5
                                                    x+2y=0

ma réponse: 1) 5x+2y=-35x+2y=-3
                         -3x-y=1   -6x-2y=2
                                                 -x=-1
                                                   x=1
                         5x+2y=-315x+6y=-9
                         -3x-y=1   -15x-5y=5
                                                      y=-4
                                       donc x=1 et y=-4


                     2) 2(x-1)=3y-5
                         x+2y=0

                         2x-2=3y-5             x+2y=0
                         2x-3y=-5+2
                         2x-3y=-3

                         2x-3y=-34x-6y=-6
                         x+2y=0  3x+6y=0
                                                    7x=-6
                                                     x=-6sur7
                                                     x=-0,86
                         2x-3y=-32x-3y=-3
                         x+2y=0-2x-4y=0
                                                   -7y=-3
                                                   y=-3sur-7
                                                   y=0,43
                                        donc x=-0,86 et y=0,43