> f1:=x->2^x;

> f2:=x->x^2;

> f3:=x->2*x;

> with(plots):

> graph1:=plot(f1(x),x=0..5,color=red):

> graph2:=plot(f2(x),x=0..5,color=blue):

> graph3:=plot(f3(x),x=0..5,color=green):

> display({graph1,graph2,graph3});