Matematika

Pertanyaan

Diketahui sistem persamaan linear 3 variabel
x+2y-3z=4
2x-y+z=3
3x-3y+2z=3

Tentukan:
A) nilai X
B) nilai y
C) nilai z
D) y+z=-x
E) himpunan penyelesaian

1 Jawaban

  • x + 2y - 3z = 4 .....(1)
    2x - y + z = 3 ......(2)
    3x - 3y + 2z = 3 .......(3)

    Eliminasi persamaan (1) dan (2) :
    x + 2y - 3z = 4 |×2|
    2x - y + z = 3 |×1|

    2x + 4y - 6z = 8
    2x - y + z = 3
    ...................................-
    5y - 7z = 5 .......(4)

    Eliminasi persamaan (1) dan (3) :
    x + 2y - 3z = 4 |×3|
    3x - 3y + 2z = 3 |×1|

    3x + 6y - 9z = 12
    3x - 3y + 2z = 3
    ....................................-
    9y - 11z = 9 ........(5)

    Eliminasi persamaan (4) dan (5) :
    5y - 7z = 5 |×9|
    9y - 11z = 9 |×5|

    45y - 63z = 45
    45y - 55z = 45
    ..................................-
    -8z = 0
    z = 0

    Substitusi z kepersamaan (4) :
    5y - 7z = 5
    5y - 7(0) = 5
    5y = 5
    y = 1

    Substitusi z dan y kepersamaan (1) :
    x + 2y - 3z = 4
    x + 2(1) - 3(0) = 4
    x + 2 -0 = 4
    x = 4 - 2
    x = 2

    Jadi :
    A) Nilai x = 2
    B) Nilai y = 1
    C) Nilai z = 0
    D) y + z = -x
    1 + 0 = - 2
    = -2 - 1 - 0
    = -3
    E) HP = {2, 1, 0}






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