jika g(x)=x+1 dan +fog)(x)=x²+3x+.Tentukanlah f(x)

(fog)x =x²+3x
f(x+1)=x²+3x
cari inversx+1= x-1
f(x-1)= (x-1)²+3(x-1)
= x²-2x+3x-3
=x²-x-3