dik f(x) = 2x + 5 dan (gof)(x)= 12x^2 + 56x + 71 nilai g(2)

Mapel : Matematika
Kelas : X SMA
Bab : Fungsi Komposisi dan Fungsi Invers

Pembahasan :
Gof(x) = 12x² + 56x + 71
G(f(x)) = 12x² + 56x + 71
G(2x + 5) = 12x² + 56x + 71

Misal 2x + 5 = a
x = (a - 5)/2

G(a) = 12[(a - 5)/2]² + 56[(a - 5)/2] + 71
G(a) = 3(a²- 10a + 25) + 28(a - 5) + 71
G(a) = 3a² - 30a + 75 + 28a - 140 + 71
G(a) = 3a² - 2a + 6
G(2) = 3(2)² - 2(2) + 6
G(2) = 14