Tentukan penyelesaian sistem persamaan berikut ;

1) 2x – 2y – 2z = 9
3x + 2y + z = 16 +
____________
5x – z = 25

2) 2x – 2y – 2z = 9 |×3|
x – 6y – 3z = -28
=> 6x – 6y – 6z = 27
x – 6y – 3z = -28 –
______________
5x – 3z = 55

3) 5x – z = 25
5x – 3z = 55 –
_________
2z = -30
z = -15

4) 5x – z = 25
5x – (-15) = 25
5x = 25 – 15
5x = 10
x = 2

5) 2x – 2y – 2z = 9
2 (x – y – z) = 9
2 (2 – y + 15) = 9
2 (17 – y) = 9
17 – y = 4,5
y = 12,5

x = 2
y = 12,5
z = -15