Решите методом подстановеи систему уравнений
решите все номера​

1. (1;-1)

2. (1;3)

3. (11;-34)

4. (2/3; -1)

Пошаговое объяснение:

1. x - 3y = 4

2x - y = 3

x = 4 + 3y

2(4 + 3y) - y = 3

x = 4 + 3y

5y = -5

x = 4 - 3 = 1

y = -1

2. 4x - y = 1

5x + 3y = 14

y = 4x - 1

5x + 3(4x - 1) = 14

y = 4x - 1

17x = 17

y = 3

x = 1

3. 7a + 2b = 9

3a + b = -1

7a + 2(-1 - 3a) = 9

b = -1 - 3a

a = 11

b = -1 - 33 = -34

4. 3x + 4y = -2

6x - 7y = 11

3x = -2 - 4y

2(-2 - 4y) - 7y = 11

3x = - 2 - 4y

-15y = 15

x = 2/3

y = -1