var('x'); y=4/(x^2+2*x-3)
yb=10; cols=['steelblue','darkblue','purple']
ll=[r'$y=%s$'%latex(y.factor()),
r'$y\prime=%s$'%latex(diff(y,x).factor()),
r'$y\prime\prime=%s$'%latex(diff(y,x,x).factor())]
p=plot([y.factor(),diff(y,x).factor(),
diff(y,x,x).factor()],(-5,3),
color=cols,thickness=1.5,legend_label=ll)
p+=sum([point((x0,y(x=x0)),color=cols[0],size=25)
p+=line([[-3,-yb],[-3,yb]],color='crimson',linestyle='-.',
thickness=3,legend_label=r'$x=-3$')
p+=line([[1,-yb],[1,yb]],color='red',linestyle='-.',
thickness=3,legend_label=r'$x=1$')
p+=line([[-5,0],[3,0]],color='magenta',linestyle=':',
thickness=3,legend_label=r'$y=0$')
p.set_legend_options(font_size=14,loc=3)
p.show(gridlines=True,figsize=(6,6),ymin=-yb,ymax=yb)
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