Y - 2 = - 4x
y = 2 - 4x
8x + 3y = 5
8x + 3 * ( 2 - 4x ) = 5
8x + 6 - 12x = 5
- 4x = - 1
x = 0,25
y = 2 - 1 = 1
ОТВЕТ ( 0,25 ; 1 )
------------------------
x + y = 7
y = 7 - x
2x + y = 8
2x + 7 - x = 8
x = 1
y = 7 - 1 = 6
ОТВЕТ ( 1 ; 6 )
---------------------
x + 5y = 7
x = 7 - 5y
3x - 2y = 4
3 * ( 7 - 5y ) - 2y = 4
21 - 15y - 2y = 4
- 17y = - 17
y = 1
x = 7 - 5 = 2
ОТВЕТ ( 2 ; 1 )