Решите систему х+5у=7
2х-у=2

Метод исключения переменных:

x + 5y = 7

2x - y = 2

-2x - 10y = -14

2x - y = 2

-11y = -12

y = 12/11

2x - 12/11 = 2

x = 17/11

(x,y) = (17/11 , 12/11)

17/11 + 5 • 12/11 = 7

2 • 17/11 - 12/11 = 2

7 = 7

2 = 2

Методом подставки:

x + 5y = 7

2x - y = 2

x = 7 - 5y

2x - y = 2

2(7 - 5y) - y = 2

y = 12/11

x = 7 - 5 • 12/11

x = 17/11

(x,y) = (17/11,12/11)

17/11 + 5 • 12/11 = 7

2 • 17/11 - 12/11 = 2

7 = 7

2 = 2