Odpowiedź:
Szczegółowe wyjaśnienie:
a)
x + y = 2x - 4y (1)
x + y = 7 - y (2)
z (2) -> x = 7 - 2y
podstawiam do (1)
7 - 2y + y = 2(7 - 2y) - 4y
7 - y = 14 - 4y - 4y
7y = 7
y = 1
x = 7 - 2y = 7 - 2 = 5
b)
3x = x - y +3 (1)
2 = y - x (2)
z (2) -> y = 2 + x
podstawiam do (1)
2x + y = 3
2x + 2 + x = 3
3x = 1
x = 1/3
y = 2 + x = 2 + 1/3 = 2 1/3
c)
2(x+2) = y-2 -> 2x +4 = y-2 -> y = 2x + 6
2x -y = x+y-15 -> x - y = -15
x - (2x + 6) = -15
-x - 6 = -15
x = 9
y = 2x + 6 = 18+6 = 24
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