Kisi Kisi PAT Matematika Kelas XI no 31

31. Diketahui 𝑔(𝑥) = 3𝑥 + 2 dan (𝑓 𝑜 𝑔)(𝑥) = 6𝑥 − 4, maka rumus 𝑓(𝑥)= ...

A. 2𝑥 − 14

B. 2𝑥 − 12

C. 2𝑥 − 10

D. 2𝑥 − 8

E. 2𝑥 − 6

Jawaban :

𝑔(𝑥) = 3𝑥 + 2 

(𝑓 𝑜 𝑔)(𝑥) = 6𝑥 − 4

f (g (x)) = 6x - 4

f (3x + 2) = 6x - 4

misalkan :

a = 3x + 2

3x = a - 2

x = 1/3 (a - 2)

f (3x + 2) = 6x - 4

f (a) = 6 (1/3 (a - 2)) - 4

f (a) = 2(a - 2) - 4

f (a) = 2a - 4 - 4

f (a) = 2a - 8

maka, 

f (x) = 2x - 8

Jawaban : D