Matematika

Pertanyaan

Jika x1 dan x2 akar akar persamaan 2^(x+1)+1/2^(x-3)=17, maka x1^2+x2^2=
A. 2
B. 5
C. 8
D. 10
E. 13

tolong dijawab pakai jalan ya

2 Jawaban

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    TerimaKasih
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  • jawab

    (2)ˣ⁺¹ + (1/2)ˣ⁻³ = 17
    (2)ˣ⁺¹ +(2⁻¹)ˣ⁻³ = 17
    (2)ˣ⁺¹ + (2)³⁻ˣ = 17
    2. 2ˣ+ 2³. 2⁻ˣ = 17

    2ˣ= a--> x = ²log a
    2a + 8/a = 17...kalikan a
    2a² -17x + 8 = 0
    (2a - 1)(a -8) = 0
    a = 1/2   atau a = 8

    a= 1/2 --> x1 = ²log 1/2 = - 1
    a= 8  --> x2 = ²log 8 = 3

    x1² + x2² = (-1)² +(3)² = 1 + 9 = 10

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