100 setxunit
7.5 setborder
90 setangle_repere
-3 3 setxrange
-1 6 setyrange
/quadrillagegray 0.4 def
0.25 setquadrillagexstep
0.25 setquadrillageystep
quadrillage
0.25 0.25 settkstep
.5 .5 setsubtkstep
0.25 0.25 setmkstep
ticks
marks
traceaxes
axesarrow
unites
/A {-2.25 2.75} def
/B {2.25 2.75} def
/C {-2 1.75} def
/D {2 1.75} def
/E {-1.5 0.5} def
/F {1.5 0.5} def
/G {2.55 4.073} def
[A B C D E F G] dashpoints

/f {setxvar
#rpn#   (1-x^2)^2/(1+x^2)
} def
/g {setxvar
#rpn#   (6/5)*x+1
} def
/u {setxvar
#rpn#   11/4
} def
gsave
   rouge
   .75 setlinewidth
   continu
 3 neg 3  {u} Courbe
grestore
/w {setxvar
#rpn#   1/2
} def
gsave
   rouge
   .75 setlinewidth
   continu
 3 neg 3  {w} Courbe
grestore

/v {setxvar
#rpn#   7/4
} def
gsave
   rouge
   .75 setlinewidth
   continu
 3 neg 3  {v} Courbe
grestore

gsave
   bleu
   .75 setlinewidth
   continu
 3 neg 3  {f} Courbe
grestore
gsave
   rouge
   .75 setlinewidth
   continu
 2 neg 3  {g} Courbe
grestore
(y = 11/4) 2.5 2.9 drtext   
(y = 7/4) 2.5 1.9 drtext   
(y = 1/2) 2.5 0.6 drtext