-1 4.5 setxrange
-1.2 1.2 setyrange

1 setxyrapport
60 setxunit
7.5 setborder
90 setangle_repere
-1 3.8 setxrange
-1.2 1 setyrange

traceaxes
axesarrow
1 xtick
2 xtick
3 xtick

/A {3 -1.2} def
/B {3 1} def

/f {setxvar
#rpn#   0.3*(-x^2+2.4*x-36/25)
} def

gsave
   noir
   0.5 setlinewidth
   continu
-1  3.5 {f} Courbe
grestore

gsave
0.5 setlinewidth
pointilles 
[A B] ligne 
grestore

[1.2 0] points

<latex>
$3$
</latex>
3 0 [1.3 dup] drtexlabel

<latex>
$-\frac{b}{2a}$
</latex>
1.2 0 [1.3 dup] uctexlabel

<latex>
$m-1<0,\Delta=0$
</latex>
2.2 -0.3 [1.3 dup] dltexlabel

<latex>
$-\frac{b}{2a}\leq 3$
</latex>
1.8 -0.6 [1.3 dup] dltexlabel