Question

Quiz 1

X + 2y + 3z = 11
2x - y - 3y = -4
-x + 2y + z = -3

NILAI 4x - 2y + z = ?

Jawaban terbaik akan di tandain, jawaban asal akan di tindak lanjuti.

Good luck :)

Answer 1

x +2y +3z = 11...............1
2x - y - 3y = -4...............2
-x +2y + z = -3..............3

eliminasi z dari pers 1 dan 2:
 x+ 2y+3z = 11
2x - y - 3y = -4 (+)
      3x + y = 7...............4

eliminasi z dari pers 1 dan 3:
x + 2y + 3z = 11
-3x+6y +3z = -9  (-)
         4x-4y = 20
             x-y = 5..............5

eliminasi y dari pers 4 dan 5:
3x+y = 7
   x-y = 5 (+)
    4x = 12
      x = 3; maka y = -2

subtitusi x = 3 dan y = -2 ke pers 1:
x +2y +3z = 11
3 +2(-2) +3z = 11
                3z = 11+1
                  z = 4

4x-2y+z = 4.(3) - 2.(-2) + 4
             = 12+4+4
             = 20

Answer 2

X + 2y + 3z = 11 | .1 = x + 2y + 3z = 11
-x + 2y + z = -3 | .3 = -3x + 6y + 3z = -9
dieleminasi
4x - 4y = 20
2x - 4y = -4
dieleminasi lagi
2x = 24
x= 12

4x - 4y = 20
4x - 8y = -8
dieleminasi lagi
4y = 28
y= 7

x+2y+3z = 11
12+2.7+3z = 11
12+14+3z= 11
26+3z= 11
3z= 11-26
z= -15/3
z= -5

=4x - 2y + z
=4.12 - 2.7 -5
=48 - 14 - 5
=29