Soal UNBK 2018 MTK IPA - no 1

Soal UNBK 2018 MTK IPA
Soal dan Pembahasan UNBK Matematika 2018
Jawaban UNBK Matematika 2018
Soal Matematika SMA 2018
Soal Ujian Akhir Matematika SMA 2018

1. Diketahui f(x) = 3x - 2 dan (f o g) (x) = 6x - 3. Nilai dari g^-1(8/3) = ...

A. 1
B. 3/2
C. 2
D. 5/2
E. 3

Jawaban : B

(f o g) (x) = 6x - 3
f ( g(x) ) = 6x - 3
3 g(x) - 2 = 6x - 3
3 g(x) = 6x -1
g(x) = 2x - 1/3

y = 2x - 1/3
y + 1/3 = 2x
x = 1/2 y + 1/6
g^-1(x) = 1/2 x + 1/6

g^-1(8/3) = 1/2 . 8/3 + 1/6
g^-1(8/3) = 8/6 + 1/6 = 9/6 = 3/2

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