Matematika

Pertanyaan

Kak tolong bantu jawab ya pakai caranya

Himpunan penyelesaian dari sistem persamaan:
3/x + 4/y + 5/z = 4
5/x - 6/y + 1/z = 17/30
6/x + 1/y - 3/z = 21/20
adalah...
A. {(-3, 4, -5/2)}
B. {(-4, -3, 5/2)}
C. {(-2, -5/2, 2)}
D. ({3, 4, 5/2)}
E. ({-3, -2, -1)}

2 Jawaban

  • Materi: Sistem persamaan

    Pembahasan d gambar
    Jawaban D
    Gambar lampiran jawaban ShanedizzySukardi
  • 3/x + 4/y + 5/z = 4
    5/x - 6/y + 1/z = 17/30
    6/x + 1/y - 3/z = 21/20

    misal :
    p = 1/x
    q = 1/y
    r = 1/z
    3p + 4q + 5r = 4 (× 1)
    5p - 6q + r = 17/30 (× 5)
    ...3p + 4q + 5r = 4
    25p - 30q + 5r = 17/6
    --------------------------------- -
    - 22p + 34q = 7/6 => pers.1

    3p + 4q + 5r = 4 (× 3)
    6p + q - 3r = 21/20 (× 5)
    ..9p + 12q + 15r = 12
    30p + 5q - 15r = 21/4
    -------------------------------- +
    39p + 17q = 69/4 => pers.2

    -22p + 34q = 7/6 (× 1)
    39p + 17q = 69/4 (× 2)
    -22p + 34q = 7/6
    78p + 34q = 69/2
    -------------------------- -
    - 100p = - 200/6
    p = (-200/6)/-100 = 200/600 = 1/3
    -22p + 34q = 7/6
    -22(1/3) + 34q = 7/6
    - 22/3 + 34q = 7/6
    34q = 7/6 + 22/3
    34q = 7/6 + 44/6
    34q = 51/6
    q = (51/6)/34
    q = (51/6) × (1/34)
    q = 51/204 = 1/4
    3p + 4q + 5r = 4
    3(1/3) + 4(1/4) + 5r = 4
    3/3 + 4/4 + 5r = 4
    1 + 1 + 5r = 4
    2 + 5r = 4
    5r = 4 - 2
    5r = 2
    r = 2/5

    p = 1/x
    1/3 = 1/x
    x = 3
    q = 1/y
    1/4 = 1/y
    y = 4
    r = 1/z
    2/5 = 1/z
    z = 5/2
    Hp = { 3 , 4 , 5/2 } (D)

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