f(x)=x-3 , g(x)=x²+x+2 jika (gof)(a) =14. nilai a =.....

Kode : 11.2.6 [Kelas 11 Matematika Bab 6 Fungsi ]
Kelas : 11
Mapel : Matematika
Kategori : Bab 6 Fungsi

f(x) = x - 3
g(x) = x² + x + 2

(gof)(x) = 14
g(f(a)) = 14
g(a - 3) = 14
(a - 3)² + (a - 3) + 2 = 14
a² - 6a + 9 + a - 3 + 2 - 14 = 0
a² - 5a - 6 = 0
(a - 2)(a - 3) = 0
a = 2   atau   a = 3