Matematika

Pertanyaan

Penyelesaian dari persamaan 5^log x + x^ log 5 = 2,5 adalah.....

2 Jawaban

  • jawab

    misalkan
    ⁵log x = a → ˣlog 5 = 1/a

    ⁵log x + ˣlog 5 = 5/2
    a + 1/a  = 5/2 .....kali 2a
    2a² + 2 = 5a
    2a² - 5a + 2 = 0
    (2a - 1)(a - 2) =0
    a= 1/2  atau x = 2

    ⁵log x = a → x = 5ᵃ
    a = 1/2  → x = 5^(1/2) = √5
    a= 2 → x = 5²= 25

    x = (√5, 25)

  • Misal :
    5'log x = a

    5'log x + x'log 5 = 5/2
    a + 1/a = 5/2
    Kedua ruas kalikan 2a
    2a² + 2 = 5a
    2a² - 5a + 2 = 0
    (2a - 1)(a - 2) = 0

    2a - 1 = 0
    a = 1/2
    5'log x = 1/2
    x = √5 ✓

    a - 2 = 0
    a = 2
    5'log x = 2
    x = 5² = 25 ✓

    NiLai x yg memenuhi :
    √5 dan 25

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