Question

помогите решить систему рівняння​

Answer 1

Ответ:

$\left \{ {x=1.5} \atop {y=2.5}} \right.$; $\left \{ {{x=\frac{2}{12}} \atop {y=-\frac{7}{6}}} \right.$

Объяснение:

1)

$\left \{ {4(x+y)-8y=-4} \atop {7(y+1)-(y+3)=19}} \right. \\\\\\\left \{ {4x+4y-8y=-4} \atop {7y+7-y-3=19}} \right.\\\\\\\left \{ {4x-4y=-4} \atop {6y+4=19}} \right.\\\\\\\left \{ {4x-4y=-4} \atop {6y=15}} \right.\\\\\\\left \{ {4x-4y=-4} \atop {y=2.5}} \right.\\\\\\\left \{ {4x-4\cdot2.5=-4} \atop {y=2.5}} \right.\\\\\\\left \{ {4x-10=-4} \atop {y=2.5}} \right.\\\\\\\left \{ {4x=6} \atop {y=2.5}} \right.\\\\\\\left \{ {x=1.5} \atop {y=2.5}} \right.$

2)

$\left \{ {{8(x+y)-12y=6} \atop {6(3x-y)+18x=13}} \right. \\\\\\\left \{ {{8x+8y-12y=6} \atop {18x-6y+18x=13}} \right. \\\\\\\left \{ {{8x-4y=6} \atop {36x-6y=13}} \right. \\\\\\\left \{ {{8x=6+4y} \atop {36x-6y=13}} \right. \\\\\\\left \{ {{x=\frac{6+4y}{8}} \atop {36x-6y=13}} \right. \\\\\\\left \{ {{x=0.75+0.5y} \atop {36x-6y=13}} \right. \\\\\\\left \{ {{x=0.75+0.5y} \atop {36\cdot(0.75+0.5y)-6y=13}} \right. \\\\\\\left \{ {{x=0.75+0.5y} \atop {27+18y-6y=13}} \right.$

$\left \{ {{x=0.75+0.5y} \atop {27+12y=13}} \right. \\\\\\\left \{ {{x=0.75+0.5y} \atop {12y=-14}} \right. \\\\\\\left \{ {{x=0.75+0.5y} \atop {y=-\frac{7}{6}}} \right. \\\\\\\left \{ {{x=0.75+0.5\cdot(-\frac{7}{6})} \atop {y=-\frac{7}{6}}} \right.\\\\\\\left \{ {{x=0.75+(-\frac{7}{12})} \atop {y=-\frac{7}{6}}} \right.\\\\\\\left \{ {{x=\frac{3}{4}-\frac{7}{12}} \atop {y=-\frac{7}{6}}} \right.\\\\\\\left \{ {{x=\frac{9}{12}-\frac{7}{12}} \atop {y=-\frac{7}{6}}} \right.$

$\left \{ {{x=\frac{2}{12}} \atop {y=-\frac{7}{6}}} \right.$

Answer 2

Объяснение:

№1

4(х + у) - 8у = -4

7(у + 1) - (у + 3) = 19

4х + 4у - 8у = -4

7у + 7 - у - 3 = 19

4х - 4у = -4 | : 4

6у + 4 = 19

х - у = -1

6у = 19 - 4

х - у = -1

6у = 15

1)

6у = 15

у = 15 : 6

у = 2,5

2)

х - у = -1

х - 2,5 = -1

х = -1 + 2,5

х = 1,5

Ответ: (1,5; 2,5)

№2

8(х + у) - 12у = 6

6(3х - у) + 18х = 13

8х + 8у - 12у = 6

18х - 6у + 18х = 13

8х - 4у = 6 | : 4

36х - 6у = 13

2х - у = 1,5

36х - 6у = 13

у = 2х - 1,5

36х - 6у = 13

1)

36х - 6у = 13

36х - 6(2х - 1,5) = 13

36х - 12х + 9 = 13

24х + 9 = 13

24х = 13 - 9

24х = 4

х = 4 : 24

х = 4/24

х = 1/6

2)

у = 2х - 1,5

у = 2 * 1/6 - 1,5

у = 2/6 - 15/10

у = 10/30 - 45/30

у = -35/30

у = -7/6

у = -1. 1/6

Ответ: (1/6; -1. 1/6)