Diketahui g(x) = x+1 dan (f°g) (x) = x^2+3x+1. Tentukan f(x) !

Kelas 10 Matematika
Bab Fungsi

(fog) (x) = x² + 3x + 1
f(x + 1) = x² + 3x + 1
f(x - 1 + 1) = (x - 1)² + 3(x - 1) + 1
f(x) = x² - 2x + 1 + 3x - 3 + 1
f(x) = x² + x - 1

(fog)(x) = f(g(x))
x^2 + 3x + 1 = f(x + 1)
f(x + 1) = x^2 + 3x + 1
f(x) = (x - 1)^2 + 3(x - 1) + 1
f(x) = x^2 - 2x + 1 + 3x - 3 + 1
f(x) = x^2 + x - 1