Решить систему 1)12x-7y=2;4x-5y=6    уравнений:                                                                                                                                                                                    ...

1) 12x - 7y = 2 4x - 5y = 6 12x - 15y = 18   8y = -16 y=-2 4x+10=6 4x=-4 x=-1   2) 4x - 7y = 30     4x - 5y = 90 -2y= -60 y=30 4x - 150=90 4x=240 x=60

1)12х-7у=2   12х-7у=2       12х-7(0,8х-1,2)=2          2)4х-7у=30     4х-7у=30          4х-7(0,8х-18) =30     4х-5у=6     5у=4х-6  /5    у=0,8х-1,2                           4х-5у=90     5у=4х-90  /5     у=0,8х-18 12х-7(0,8х-1,2)=2               у=0,8*(-1)-1,2=                4х-7(0,8х-18) =30                   у=0,8*60-18=30 12х-5,6х+8,4=2                    =-2                                    4х-5,6х+126=30 6,4х=2-8,4                                                                       -1,6х=30-126 6,4х=-6,4  /6,4                                                                 -1,6х=-96 х=-1                                                                                   х=60 Ответ:1) х=-1; у=-2. 2) х=60; у=30