Matematika

Pertanyaan

Diketahui SPLTV 4x + 3y + z = 16 2x + 7y + 3z = 8 x – 3y – 2z = - 14 carilah himpunan penyelesaiannya

1 Jawaban

  • 4x + 3y + z = 16....(1)
    2x + 7y + 3z = 8...(2)
    x - 3y - 2z = -14...(3)
    ○> eliminasi z dari pers. (1) &(2)
    4x + 3y + z = 16|×3
    2x + 7y + 3z = 8|×1
    12x + 9y + 3z = 48
    2x + 7y + 3z = 8
    ---------------------------- -
    10x + 2y = 40.....(4)
    ○> eliminasi z dari pers. (1) & (3)
    4x + 3y + z = 16|×2
    x - 3y - 2z = -14|×1
    8x + 6y + 2z = 32
    x - 3y - 2z = -14
    -------------------------- +
    9x + 3y = 18....(5)
    ○> eliminasi y dari pers. (4) & (5)
    10x + 2y = 40|×3
    9x + 3y = 18|×2
    30x + 6y = 120
    18x + 6y = 36
    ---------------------- -
    12x = 84
    x = 84/12
    x = 7
    ○> subtitusi x = 7 ke pers. (5)
    9(7) + 3y = 18
    63 + 3y = 18
    3y = 18-63
    y = -45/3
    y = -15
    ○> subtitusi x=7 & y=-15 ke pers. (3)
    7 - 3(-15) - 2z = -14
    7 + 45 - 2z = -14
    52 - 2z = -14
    -2z = -14-52
    z = -66/-2
    z = 33
    jadi, himpunan penyelesaian dari sistem pers. tsb adalah
    {(7, -15, 33)}

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