Matematika

Pertanyaan

Selesaikan himpunan penyelesaian persamaan berikut

1. 4x+2y+z = 6
2x+3y-z =6,5
3x+2y+2z = 7


2. 3x+2y+z=12
4x+3y+2z=17
x+y+3z=5

tolong jawab dengan cara

1 Jawaban

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    Nomor 1:
    4x + 2y + z = 6 → pers.1
    2x + 3y - z = 6,5 → pers.2
    3x + 2y + 2z = 7 → pers.3

    Eliminasi pers.1 dan 2
    4x + 2y + z = 6
    2x + 3y - z = 6,5
    ____________+
    6x + 5y = 12,5 → pers.4

    Eliminasi pers. 1 dan 3
    4x + 2y + z = 6
    3x + 2y + 2z = 7
    Pers.1 dikali 2
    8x + 4y + 2z = 12
    3x + 2y + 2z = 7
    _____________-
    5x + 2y = 5 → pers.5

    Eliminasi pers.4 dan 5
    6x + 5y = 12,5
    5x + 2y = 5
    Pers.4 dikali 2 dan pers.5 dikali 5
    12x + 10y = 25
    25x + 10y = 25
    ___________-
    -13x = 0
    x = 13

    Substitusikan nilai x ke pers.5
    5x + 2y = 5
    65 + 2y = 5
    2y = 5 - 65
    2y = -60
    y = -30

    Substitusikan nilai x dan y ke pers.1
    4x + 2y + z = 6
    52 - 60 + z = 6
    -8 + z = 6
    z = 14

    HP = {(13, -30, 14)}

    Nomor 2:
    3x + 2y + z = 12 → pers.1
    4x + 3y + 2z = 17 → pers.2
    x + y + 3z = 5 → pers.3

    Eliminasi pers.1 dan 2
    3x + 2y + z = 12
    4x + 3y + 2z = 17
    Pers.1 dikali 2
    6x + 4y + 2z = 24
    4x + 3y + 2z = 17
    _____________-
    2x - y = 7 → pers.4

    Eliminasi pers.1 dan 3
    3x + 2y + z = 12
    x + y + 3z = 5
    Pers.1 dikali 3
    9x + 6y + 3z = 36
    x + y + 3z = 5
    _____________-
    8x - 5y = 31 → pers.5

    Eliminasi pers.4 dan 5
    2x - y = 7
    8x - 5y = 31
    Pers.1 dikali 4
    8x - 4y = 28
    8x - 5y = 31
    _________-
    y = -3

    Substitusikan nilai y ke pers.4
    2x - y = 7
    2x + 3 = 7
    2x = 4
    x = 2

    Substitusikan nilai x dan y ke pers.1
    3x + 2y + z = 12
    6 - 6 + z = 12
    z = 12

    HP = {(2, -3, 12)}

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