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Ответы
Ответ:
1) (x,y) = (-2,8)
2)(x,y) = (-4,8)
3)(x,y) = (7, -1)
4) (x,y) = (5,-2)
Объяснение:
СПОСІБ ПІДСТАНОВКИ
1.
1) x + y = 6
x +2y = 14
2) x = 6 - y
x +2y = 14
6-y+2y = 14
6+y = 14
y = 14-6
y = 8
x = 6-8
x = -2
3) -2+8 = 6
-2+2*8 = 14
4) 6 = 6
14 = 14
Отже (x,y) = (-2,8)
2.
1) x+2y = 12
3x+2y = 4
2) 2y = 12-x
3x+2y = 4
3x+12-x = 4
2x+12 = 4
2x = -8
x = -4
3*(-4)+2y = 4
-12+2y = 4
2y = 16
y = 8
3) -4+2*8 = 12
3*(-4)+2*8 = 4
4) 12 = 12
4 = 4
Отже (x,y) = (-4,8)
3.
1) x-3y = 10
x+y = 6
2) x-3y = 10
x = 6-y
6-y-3y = 10
6-4y = 10
-4y = 4
y = -1
x = 6 - (-1) = 7
3) 7-3*(-1) = 10
7+(-1) = 6
4) 10 = 10
6 = 6
Отже (x,y) = (7,-1)
4.
1) x-4y = 13
2x+y = 8
2) x = 13+4y
2x+y = 8
2(13+4y)+y = 8
26+8y+y = 8
26+9y = 8
9y = =18
y = -2
x = 13+4(-2) = 5
3) 5-4(-2) = 13
2*5+(-2) = 8
4) 13 = 13
8 = 8
(x,y) = (5,-2)