Matematika

Pertanyaan

Tentukan himpunan penyelesaian dari

2/x - 1/y + 2/z = 1
3/x + 2/y - 3/z = -8
1/x - 4/y - 1/z = 2

1 Jawaban

  • misal a = 1/x , b = 1/y dan c = 1/z
    maka :
    2a - b + 2c = 1
    3a + 2b - 3c = -8
    a - 4b - c = 2

    2a - b + 2c = 1 (× 2)
    3a + 2b - 3c = -8 (× 1)

    4a - 2b + 4c = 2
    3a + 2b - 3c = -8
    ------------------------- +
    7a + c = -6 => pers.I

    2a - b + 2c = 1 (× 4)
    a - 4b - c = 2 (× 1)

    8a - 4b + 8c = 4
    ...a - 4b - ...c = 2
    ------------------------ -
    7a + 9c = 2 => pers.II


    pers.I => .7a + c = -6
    pers.II => 7a + 9c = 2
    .................------------------ -
    .........................-8c = -8
    .............................c = -8/-8 = 1
    7a + c = -6
    7a + 1 = -6
    7a = -6 - 1
    7a = -7
    a = -7/7 = -1

    2a - b + 2c = 1
    2(-1) - b + 2(1) = 1
    -2 - b + 2 = 1
    -b = 1
    b = 1/-1 = -1

    maka :
    a = 1/x
    -1 = 1/x
    x = -1

    b = 1/y
    -1 = 1/y
    y = -1

    c = 1/z
    1 = 1/z
    z = 1

    Jadi HPnya adalah {-1 , -1 , 1}

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