import graph_pi;
size(7.5cm,0);

real f(real x){return (x+1)*(9-x)/4;}

graphicrules(unit=1cm,xmin=-1, xmax=7, ymin=0, ymax=7);
draw(graph(f),1bp+blue);
draw(graph(new real(real x){return x;}),.6bp+grey);
cartesianaxis(xticks=LeftTicks("%",pTick=1bp+.8grey, ptick=grey),
            yticks=LeftTicks("%",pTick=1bp+.8grey, ptick=grey));
draw(recursivegraph(f,-.5,n=16),
     recursiveoption(Label(scale(.75)*"v"),
                     labelinner=false,
                     format="=%.2f",
	         px=dashed+.6bp+grey,
			 automarker=nomarker),
     .6bp+red);
label("$u_{n+1}=\frac{(u_n+1)(9-u_n)}{4}$",(3,8));