Matematika

Pertanyaan

Sistem persamaan linear 3 variabel
1. 2x - y = 5
3y + z = 0
x + 4z = 14
Tentukan himpunan penyelesaiannya

2. 2x + 3y - z = 5
x + y + z = 9
x - 2y - z = -7
Tentukan himpunan penyelesaiannya

2 Jawaban

  • 1) 2x - y = 5 => 2x = y + 5 => x = (y + 5)/2
    2) 3y + z = 0 => z = -3y
    3) x + 4z = 14
    => (y + 5)/2 + 4(-3y) = 14 ==> kedua ruas kali 2
    => y + 5 - 24y = 28
    => -23y = 23
    => y = -1
    x = (y + 5)/2 = (-1 + 5)/2 = 4/2 = 2
    z = -3y = -3(-1) = 3
    HP = {(2, -1, 3)}


    1) 2x + 3y - z = 5
    2) x + y + z = 9
    3) x - 2y - z = -7
    Eliminasi 1) dan 2)
    2x + 3y - z = 5
    x + y + z = 9
    -------------------- +
    3x + 4y = 14 ....... (4)
    Eliminasi 2) dan 3)
    x + y + z = 9
    x - 2y - z = -7
    -------------------- +
    2x - y = 2 ........... (5)
    Eliminasi (4) dan (5)
    3x + 4y = 14 |.1| 3x + 4y = 14
    2x - y = 2 |. 4 | 8x - 4y = 8
    --------------------------------------- +
    ............................ 11x = 22 => x = 2
    (5) 2x - y = 2
    => 2(2) - y = 2
    => 4 - y = 2
    => y = 2
    (2) x + y + z = 9
    => 2 + 2 + z = 9
    => z = 5
    HP = {(2, 2, 5)}
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