import graph_pi;

real f(real x){return -x^3/8-x^2/4+2x;}

graphicrules(xunit=6cm,yunit=4cm,
             xmin=.9, xmax=2.1, ymin=0, ymax=3);

draw(graph(f));
draw(graph(new real(real x){return x;}), grey);
cartesianaxis(xticks=NoTicks,viewyaxis=false);

draw(recursivegraph(f,1,n=5),
     recursiveoption(Label(scale(.75)*"v"),
                     labelinner=false,
                     format="=%.2f"),
     .8red);