Please help me, kok ada huruf g disitu

Sepertinya itu salah ketik bukan g tetapi 9
(f o g)(x) = 9x^2 - 6x + 1
f(g(x)) = 9x^2 - 6x + 1
f(3x - 2) = 9x^2 - 6x + 1
Misal
3x - 2 = a => 3x = a + 2 => x = (a + 2)/3
f(a) = 9((a + 2)/3)^2 - 6(a + 2)/3 + 1
f(2) = 9((2 + 2)/3)^2 - 6(2 + 2)/3 + 1
f(2) = 9(4/3)^2 - 6 (4/3) + 1
f(2) = 9 (16/9) - 8 + 1
f(2) = 16 - 8 + 1 = 9

g(x) = 3x - 2
g(2) = 3(2) - 2 = 4

(f - g)(2) = f(2) - g(2) = 9 - 4 = 5