Matematika

Pertanyaan

Jika 4*3 log a + 3*3 log b = 6 dan 3 log b - 2*3 log a = -8, maka ab^2 adalah...

1 Jawaban

  • 4 . ³log a + 3 . ³log b = 6
    ³log b - 2 . ³log a = - 8
    Misal
    ³log a = x
    ³log b = y

    4x + 3y = 6 ... (1)

    -2x + y = -8
    y = -8 + 2x ... (2)

    »Substitusi (2) ke (1)
    4x + 3(-8 + 2x) = 6
    4x - 24 + 6x = 6
    10x = 30
    x = 3

    » Substitusi x = 3 ke (2)
    y = -8 + 2(3)
    y = -2

    ³log a = 3
    ³log a = ³log 27
    a = 27

    ³log b = -2
    ³log b = ³log(1/9)
    b = 1/9

    maka,
    ab²
    = 27 x (1/9)²
    = 27 x 1/81
    = 1/3


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