Project raised exception class EInvalidOp with message ‘Invalid floating point operation’

procedure TForm1.Button1Click(Sender: TObject);
var
x, y, z, fx: extended;
e: real;
begin
 x := strtofloat(Edit1.Text);
 y := strtofloat(Edit2.Text);
 e := 2.71;
 case RadioGroup1.ItemIndex of
 0: fx := (exp(ln(e)*x))-(exp(ln(e)*(-x))/2);
 1: fx := exp(ln(x)*2);
 2: fx := exp(ln(e)*x);
end;
 if x-y=0 then z := ((fx*fx)+y*y+sin(y)) else
 if x-y>0 then z := (y*y-(2*y*fx)+(fx*fx))+sin(y)/cos(y) else z := (((fx*fx)+y*y-(2*fx*y)+cos(y)));
 if CheckBox1.Checked then
 Memo1.Lines.Add('X ='+Edit1.Text+' Y ='+Edit2.Text);
 Memo1.Lines.Add('Z ='+floattostrF(z,ffFixed,8,3));
end;
end.

// подключи только пакет Math в uses
procedure TForm1.Button1Click(Sender: TObject);
const
  EX = 2.71;
var
  x, y, z, fx: Extended;
begin
  x := strtofloat(Edit1.Text);
  y := strtofloat(Edit2.Text);
  case RadioGroup1.ItemIndex of
    0:
      fx := (Exp(ln(EX) * x)) - (Exp(ln(EX) * (-x)) / 2);
    1:
      fx := Exp(ln(x) * 2);
    2:
      fx := Exp(ln(EX) * x);
  end;
  if x - y = 0 then
    z := (Power(fx, 2) + Power(y, 2) + sin(y))
  else if x - y > 0 then
    z := Power(y, 2) - (2 * y * fx) + Power(fx, 2) + sin(y) / cos(y)
  else
    z := Power(fx, 2) + y * y - (2 * fx * y) + cos(y);
  if CheckBox1.Checked then
    Memo1.Lines.Add('X =' + Edit1.Text + ' Y =' + Edit2.Text);
  Memo1.Lines.Add('Z =' + floattostrF(z, ffFixed, 8, 3));
end;