Question

розв'яжи систему рівнянь способом додавання ​

Answer 1

Ответ:

б)

-10у= -80

у=8

-6х+8= -29

-6х= -37

х=37/6

(37/6;8)

в)

{0,5х-0,3у= -1 |*10

{1,5х+0,4у=10 |*10

{5х-3у= -10 |*(-3)

{15х+4у=100

{-15х+9у=30

{15х+4у=100

13у=130

у=10

5х-3*10= -10

5х-30= -10

5х=20

х=4

(4;10)

Answer 2

б)

$- 6x + y = - 29 \\ 6x - 11y = - 51 \\ \\ - 11y + y = - 29 - 51 \\ - 10y = - 80 \\ 10y = 80 \\ y = 80 \div 10 \\ y = 8 \\ \\ 6x - 11 \times 8 = - 51 \\ 6x - 88 = - 51 \\ 6x = - 5 1+ 88 \\ 6x = 37 \\ x = \frac{37}{6} \\ x = 6 \frac{1}{6}$

Ответ: ( 6 1/6 ; 8 )

в)

$0.5x - 0.3y = - 1 \: \: | \times 10\\ 1.5x + 0.4y = 10 \: \: | \times 10 \\ \\ 5x - 3y = - 10 \: \: | \times 4 \\ 15x + 4y = 100 \: \: | \times 3 \\ \\ 20x -1 2y = - 40 \\ 45x + 12y = 300 \\ \\ 20x + 45 x= 300 - 40 \\ 65x = 260 \\ x = 260 \div 65 \\ x = 4 \\ \\ 15 \times 4 + 4y = 100 \\ 60 + 4y = 100 \\ 4y = 100 - 60 \\ 4y = 40 \\ y = 40 \div 4 \\ y = 10$

Ответ: ( 4 ; 10 )