x-3y=9-2z 2x+4y-3z=-9 3x-2y+5z=12 nilai x+y-z adalah

x - 3y + 2z = 9 (i)
2x + 4y - 3z = -9 (ii)
3x - 2y + 5z = 12 (iii)

Eliminasi i dgn ii
x - 3y + 2z = 9 |x 2|
2x + 4y - 3z = -9

2x - 6y + 4z = 18
2x + 4y -3z = -9
---------------------- (-)
-10y + 7z = 27 (iv)

Eliminasi ii dan iii
2x + 4y - 3z = -9 |x 3|
3x - 2y + 5z = 12 |x 2|

6x + 12y - 9z = -27
6x - 4y + 10z = 24
------------------------(-)
16y - 19z = -51 (v)

Eliminasi iv dan v
-10y + 7z = 27 |x 19|
16y - 19z = -51 |x 7|

-190y + 133z = 513
112y - 133z= -357
----------------------- (+)
-78y = 156
y= -2

-10y + 7z = 27
-10(-2) + 7z = 27
7z= 27 - 20
z = 7 : 7 = 1

x - 3y + 2z = 9
x = 9 - 2(1) + 3(-2)
x = 9 - 8
x= 1

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