Mohon bantuan nya, jika f(x) = x-3 dan g(x)=2x+4 ,maka (fog)^-1 (4) = ….

Diket :
f(x) = x-3
g(x) = 2x + 4
dit : (fog)² – 1 (4) = …
jwb :
(fog)² – 1 = (gf(x))² -1 <=> (2(x-3)-4)²
                            (2x-10)² = 4x² – 40x + 100 – 1 = 4x² – 40x + 99
(fog)²(4) = 4(4)² – 40(4) + 99
            = 64 – 160 + 99 = 3