1)
x+y=2
2x-y=65
у = 2-х
2х - (2-х) = 65
2х - 2 + х = 65
3x = 67
x = 22 1/3
y = 2-x
y = 2 - 22 1/3 = -20 1/3
х = 22 1/3
y = -20 1/3
Ответ: (22 1/3; -20 1/3)
2) x+y =8
2x+y=6
y = 8-x
2x + (8-x) = 6
2x + 8 - x = 6
x = -2
y = 8 - x
y = 8 - (-2) = 8+2 = 10
x = -2
y = 10
Ответ: (-2;10)
3) x-2y =12
x- y = 4
x-2y = 12
x = y+4
y+4 - 2y = 12
-y = 8
y = -8
x = y + 4
x = -8+4 = -4
x = -4
y = -8
Ответ: (-4;-8)