信任求助，哪里出错了？

implementation
{$R *.dfm}
function f(x:Real):Real;
begin
f:=2*x;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
i,x,y,s,b: Real;
n,j:Integer;
const
a=1;
H=99;
m=100;
begin
Button1.Caption:= '积分结果 ';
j:= StrToInt(edit1.Text); //分成j等分，edit1中先输入的值
i:=(b-a)/j;
y:=0;
for n:=1 to j do
begin
x:= a+(n-1)*i ;
y:=y+ f(x); //即f（a）+f（a+i）+f（a+2i）+···的值
end;
s:=y*(b-a)/j ; //总面积的值
for b:= a to m do
begin
If s=H then
break;
end;
If s=H then
b:=b;
end;
edit1.Text:='';
edit1.Text:= floattostr(b);
end;
end.