Fungsi f:R ->R dinyatakan oleh f(x) =x+2 dan g o f (x) =2x^2+4x+1 maka g(2x)

(gof) (x) = 2x²+4x+1
g(x+2) = 2x²+4x+1
misal
t=x+2
x=t-2
maka
g(x) = 2(t-2)²+4(t-2)+1
= 2(t²-4t+4)+4t-8+1
=2t²-8t+8-4t-7
=2t²-12t+1
g(x) = 2x²-12x+1

ditanya g(2x)
misal
t=2x
x=t/2
maka
g(x) = 2(t/2)²-12(t/2)+1
=2t²/4 -6t+1
=½t²-6t+1
jadi
g(2x) = ½x²-6x+1

fungsi komposisi

f(x) = x+2
gof(x)= 2x² + 4x + 1
g(x+2) = 2x²+ 4x +1
g(x)= 2(x-2)² + 4(x-2) + 1
g(x)= 2(x²-4x+4) + 4x - 8 + 1
g(x)= 2x²-8x +8 + 4x -8 + 1
g(x)= 2x² - 4x + 1
g(2x)= 2(2x)² - 4(2x) + 1
g(2x) = 8x² -8x  + 1