Diketahui f(x) = 3x+2. Dan (g°f) (x) = 8-6x Ditanyakan g(x)?

jawab

f(x) = 3x+2
gof(x) = 8 - 6x
g { f(x)}= 8 - 6x
g (3x+2) = 8 - 6x
3x + 2 = y
3x = y-2
x = 1/3 (y-2)
g(y) = 8 - 6{ 1/3 (y-2)}
g(y)=  8 - 2(y-2)
g(x) = 8 -2(x-2) = 8 - 2x + 4
g(x) = 12 - 2x

mis : 3x+2=a
         x=(a-2)/3

f(x) = 3x + 2
(g°f) (x) = -6x+8
g(3x+2) = -6x+8
g(a) = -6x+8
g(a) = -6((a-2)/3)+8
g(a) = -2a+12

Jadi, g(x) = -2x+12