import graph_pi;

real f(real x){return -.8x+3;}

graphicrules(unit=1cm,
             xmin=-2, xmax=6, ymin=-2, ymax=6);

draw(graph(f));
draw(graph(new real(real x){return x;}), grey);
cartesianaxis();
draw(recursivegraph(f,-1.8,n=7),.8red);