bagaimana cara kerjanya?

dik : ( fog) (x) = 4x-6
f(x) = 2x- 4
dit: g(x)=.....
jawab :
misalkan : g (x) : a
(fog) (x) = 4x-6
f (g(x)) = 4x- 6
f(a) =4x-6
2a - 4 = 4x - 6
2a = 4x- 6 + 4
2a = 4x - 2
a = 4x - 2 ÷2
= 2 ( 2x - 1 ) ÷ 2
= 2x- 1
a = g (x) = 2x - 1