x + y + z = 2
x - y + 5z = 6
cancelando +y com -y:
x + z = 2*(-5)
x + 5z = 6
-5x -5z = -10
...x +5z = 6
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-4x = -4 *(-1)
4x = 4
x = 4/4
x = 1
x + z = 2
1 + z = 2
z = 2 - 1
z = 1
x + y + z = 2
1 + y + 1 = 2
2 + y = 2
y = 2 - 2
y = 0
S: {x, y, z} = {1, 0, 1}
