> y[ex]:=x->6/x+3*x-9;

                     y[ex] := x -> 6/x + 3 x - 9

> y[I]:=x->15*(x-1)*(x-2)/8;

                  y[I] := x -> 15/8 (x - 1) (x - 2)

> y[II]:=x->(1422-2595*x+1404*x^2-231*x^3)/179;

                          1422   2595     1404  2   231  3
            y[II] := x -> ---- - ---- x + ---- x  - --- x
                          179    179      179       179

> y[a]:=x->-508791*(x-1)*(3-2*x)/142942-71379*(x-1)*(4*x-5)/71471;

                 508791                     71379
   y[a] := x -> ------- (x - 1) (3 - 2 x) - ----- (x - 1) (4 x - 5)
                 142942                     71471

> y[b]:=x->-71379*(2-x)*(7-4*x)/71471-366261*(2-x)*(2*x-3)/142942;

                 71379                     366261
   y[b] := x -> ------ (2 - x) (7 - 4 x) - ------ (2 - x) (2 x - 3)
                 71471                     142942

> plot1:=plot({y[ex](x),y[I](x),y[II](x)},x=1..2):
> plot2:=plot(y[a](x),x=1..3/2):
> plot3:=plot(y[b](x),x=3/2..2): plots[display]({plot1,plot2,plot3});

> 
> 
