a)
(fog)(0)=f(g(0))=f(-3)=2•(-3)+1=-6+1=-5
g(0)=0-3=-3
(gof)(1)=g(f(1))=g(3)=3-3=0
f(1)=2•1+1=2+1=3
(fof)(-1)=f(f(-1))=f(-1)=-1
f(-1)=2•(-1)+1=-2+1=-1
(gog)(1)=g(g(1))=g(-2)=-2-3=-5
g(1)=1-3=-2
b)
(fog)(x)=f(g(x))=f(x-3)=2(x-3)+1=2x-6+1=2x-5
(gof)(x)=g(f(x))=g(2x+1)=2x+1-3=2x-2
(fof)(x)=f(f(x))=f(2x+1)=2(2x+1)+1=4x+2+1=
=4x+3
