Question

{ x - y + 2z =-5
{2x + y + z =-1
{ x + y - z =3

Answer 1

2x + y + z = -1
x + y - z = 3
------------------ -
x + 2z = -4

x - y + 2z = -5
2x + y + z = -1
------------------ +
3x + 3z = -6

x + 2z = -4 dikalikan 3 => 3x + 6z = -12
3x + 3z = -6 dikalikan 1 => 3x + 3z = -6
------------------ -
3z = -6
z = -2

x + 2z = -4
x + 2 (-2) = -4
x -4 = -4
x = 0

x + y - z = 3
0 + y - (-2) = 3
y + 2 = 3
y = 1