g°f = 2x + 4x + 5 dan g(x) = 2x + 3 rumus fungsi f

gof(x)=2x+4x+5=6x+5
6x+5=2(f(x))+3
6x+5-3=2(f(x))
f(x)=(6x+2)/2
f(x)=3x+1

gof(x)=2x^2+4x+5
2(f(x))+3=2x^2+4x+5
2(f(x))=2x^2+4x+2
f(x)=x^2+2x+1