Question

1. jika f(x) =3x-3 maka nilai f-1 (2) adalah .....
2. jika g(x) =2x +7 maka nilai g-1(2) adalah....
3. jika f(x) =2x+3 dan g(x) = 2x^2 - 5 x +2 tentukan (gof)(x)....
4. jika f(x) = 3x^2 +9 dan g(x) = 2x+1 tentukan (fog)(x)

Answer 1

No.3
(gof)(x) = (g(f(x))
= g(2x+ 3)
= 2(2x+3)^2 - 5(2x+3) + 2
= 2(4x^2 + 12x+9) - 10x - 15 + 2
= 8x^2 + 24x + 18 - 10x - 15 + 2
= 8x^2 + 14x + 5

No.4
(fog)(x) = (f(g(x))
= f(2x+1)
= 3(2x+1)^2 + 9
= 3(2x^2 + 4x + 1) + 9
= 6x^2 + 12x + 3 + 9
= 6x^2 + 12x + 12 atau x^2+2x+2