Jawaban:

2. x+y- z = 24 ....pers. (1)

2x-y+2z = 4 ....pers. (2)

x+2y-3z= 36 ....pers. (3)

eliminasi pers. (1) dan (2)

x+y- z = 24

2x-y+2z = 4 +

3x + z = 28 ....(4)

kemudian pers. (1) dan (3)

x+y- z = 24 (kali 2)

x+2y-3z = 36 -

2x+2y-2z=48

x+2y-3z=36 -

x+z = 12 .... pers.(5)

pers. (4) dan (5)

3x+z=28

x+z = 12 -

2x = 16

x = 16/2 = 8

masukkan nilai x ke pers. (4)

3x+z=28

3(8)+z = 28

24 + z = 28

z = 28-24 = 4

masukkan nilai x dan z ke pers.(1)

x+y-z=24

(8)+y-(4)= 24

y = 24-4

y = 20

nilai x : y : z = 8 : 20 : 4

= 2 : 5 : 1

3. x-y+2z=5 .... pers.(1)

x-2y+3z=4 .... pers.(2)

2x+y-z=9 ..... pers.(3)

eliminasi pers. (1) dan (2)

x-y+2z=5

x-2y+3z=4 -

y - z = 1 .... pers.(4)

lalu per. (1) dan (3)

x-y+2z=5 (kali 2)

2x+y-z=9

2x-2y+4z=10

2x+ y - z=9 -

-3y+5z = 1 .... pers.(5)

pers. (4) dan (5)

y - z = 1 (kali 3)

-3y+5z = 1

3y-3z=3

-3y+5z=1 +

-2z=4

z = -2

masukkan nilai z ke pers.(4)

y-z=1

y-(-2)=1

y = 1-2

y = -1

masukkan nilai y dan z ke pers.(1)

x-y+2z=5

x-(-1)+2(-2)=5

x+1-4=5

x = 5+3

x= 8