solve by addition method
x +3y +z =6
3x + y – z = -2
2x +2y – z = 1
add first two
4 x + 4 y = 4 or x+y = 1 or 3x + 3 y = 3
or -3 x - 3 y = - 3
add first to third
3 x + 5 y = 7
now add that to
-3 x - 3 y = - 3
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0 + 2 y = 4
y = 2 (we are on a roll)
we know x+y = 1 so x = -1
then us eqn 1
-1 + 2(2) + z = 6
3 + z = 6
z = 3
the end