Matematika

Pertanyaan

17. Diketahui 1/4x + 2/3y = 2 1/2 dan 3/4x + 1/2y = 3. Nilai 3x + 2y =..

1 Jawaban

  • 1/4.x + 1/6.y = 4
    [x/4 + y/6 = 4]×24
    6x + 4y = 96
    3x + 2y = 48 ...(1)

    1/2.x - 2/3.y = -2
    [x/2 - 2y/3 = -2]×6
    3x - 4y = -12 ...(2)

    3x+2y=48
    3x-4y=-12
    ___________—
    6y = 6
    y = 10 ...(3)

    3x-4y = -12
    3x-40 = -12
    3x = 28
    x = 28/3 ...(4)

    maka, 
    3x - 2y - 5 
    = 3(28/3) - 2(10) - 5 
    = 28-20-5
    = 3

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