Построение графика функции!

uses graph;
const a=8.5;
      b=0.85;
function F(x,l:real):real;
begin
F:=a*exp(b*x+l*x*x);
end;
var xc,yc,i:integer;
    mx,my,x,dx,max:real;
    s:string;
begin
initgraph(xc,yc,'');
xc:=getmaxX div 2;
yc:=getmaxY-40;
mx:=xc-30;
my:=(yc-20)/F(1,0.5);
line(30,yc,getmaxX-30,yc);
line(xc,20,xc,getmaxY-20);
outtextXY(getmaxX-30,yc-15,'X');
outtextXY(xc+10,20,'Y');
line(xc-round(mx),yc+3,xc-round(mx),yc-3);
line(xc+round(mx),yc+3,xc+round(mx),yc-3);
outtextXY(xc-round(mx),yc+10,'-1');
outtextXY(xc+round(mx),yc+10,'1');
outtextXY(xc+5,yc+10,'0');
line(xc-3,yc-round(F(-1,-0.5)*my),xc+3,yc-round(F(-1,-0.5)*my));
line(xc-3,yc-round(F(1,0.5)*my),xc+3,yc-round(F(1,0.5)*my));
str(F(1,0.5):0:2,s);
outtextXY(xc-45,yc-round(F(1,0.5)*my),s);
str(F(-1,-0.5):0:2,s);
outtextXY(xc-40,yc-round(F(-1,-0.5)*my),s);
x:=-1;
while x<=1 do
 begin
  putpixel(xc+round(x*mx),yc-round(F(x,-0.5)*my),10);
  putpixel(xc+round(x*mx),yc-round(F(x,0)*my),11);
  putpixel(xc+round(x*mx),yc-round(F(x,0.5)*my),13);
  x:=x+0.001;
 end;
setcolor(14);
outtextXY(10,40,'Grafiki functii y=8.5e^(0.85x+lx^2)');
outtextXY(70,60,'na intervale [-1;1]');
setcolor(10);
outtextXY(100,80,'l=-0.5');
setcolor(11);
outtextXY(100,100,'l=0.0');
setcolor(13);
outtextXY(100,120,'l=0.5');
readln
end.