load("plot.o");
plot_options:cons([nticks,40],plot_options);
show_newton(expr,pt,m):=
block([numer:true],
  kill(xx), 
  define(ff(x), expr),
  define(fp(x),diff(expr,x)),
  xx[0]:pt,
  xx[n]:=xx[n-1]-ff(xx[n-1])/fp(xx[n-1]),
  lis:append([expr],create_list(expand(fp(xx[n])*(x-xx[n])+ff(xx[n])),n,0,m-1)),
  plot2dopen(lis,[x,min(-3,pt-3),max(pt+3,4)],[y,-200,200])
     );done;