一元2次方程的根的问题

Question

var
a,b,c:integer;
p:int64;
x1,x2:string;
begin
  a:=strtoint(edit1.Text);
  b:=strtoint(edit2.Text);
  c:=strtoint(edit3.Text);
  p:=b*b-4*a*c;
  edit6.Text:=floattostr(p);
   if p>=0 then
    begin
      try
        x1:=floattostr(-b/2+sqr(p));
        x2:=floattostr((-b/2-sqr(p));
         edit4.Text:=x1;
         edit5.Text:=x2;
         except
           showmessage('溢出');
     end;
    if p<0 then
     begin
       try
         x1:=floattostr(-b/2)+'i'+floattostr(sqr(-p));
         x2:=floattostr(-b/2)+'-'+'i'+floattostr(sqr(-p));
         edit4.Text:=x1;
         edit5.Text:=x2;
         except
           showmessage('溢出');
     end;
  end; end;
 end;
计算出来的结果跟实际的不相符

Answer 1

拜托,公式对吗?
x1:=FloatToStr((-b+sqrt(p))/(2*a));
x2:=FloatToStr((-b-sqrt(p))/(2*a));
虚数那部分以此类推.

Answer 2

非常感谢jorge 的提醒 
可是虚数不能计算
而且
好象还捕获不到异常

Answer 3

第二个if有错
if p<0 then
    begin
      try
        x1:=floattostr(-b/2))+'+'+'i'+floattostr(sqr(-p));
         x2:=floattostr(-b/2)+'-'+'i'+floattostr(sqr(-p));
         edit4.Text:=x1;
         edit5.Text:=x2;
         except
           showmessage('溢出');

Answer 4

测试过 还是有问题
比如a：=1 b：=3 c;=1 
计算出x1=11 x2：=11

Answer 5

var
a,b,c:integer;
p:int64;
x1,x2:string;
begin
  a:=strtoint(edit1.Text);
  b:=strtoint(edit2.Text);
  c:=strtoint(edit3.Text);
  p:=b*b-4*a*c;
  edit6.Text:=floattostr(p);
   if p>=0 then
    begin
      try
        x1:=floattostr((-b+sqr(p))/2/a);
        x2:=floattostr((-b-sqr(p))/2/a);
         edit4.Text:=x1;
         edit5.Text:=x2;
         except
           showmessage('溢出');
     end;
    if p<0 then
     begin
       try
         x1:=floattostr(-b/2))+'+'+'i'+floattostr(sqr(-p));
         x2:=floattostr(-b/2)+'-'+'i'+floattostr(sqr(-p));
         edit4.Text:=x1;
         edit5.Text:=x2;
         except
           showmessage('溢出');
     end;
  end; end;
 end;

Answer 6

procedure TForm1.Button1Click(Sender: TObject);
var
a,b,c:integer;
p:int64;
x1,x2:string;
begin
  a:=strtoint(edit1.Text);
  b:=strtoint(edit2.Text);
  c:=strtoint(edit3.Text);
  p:=b*b-4*a*c;
  edit6.Text:=floattostr(p);   if p>=0 then
    begin
      try
        x1:=floattostr((-b+sqr(p))/2/a);
        x2:=floattostr((-b-sqr(p))/2/a);
         edit4.Text:=x1;
         edit5.Text:=x2;
         except
           showmessage('溢出');
       end
     end
    else 
    if p<0 then
     begin
       try
         x1:=floattostr(-b/2)+'+'+'i'+floattostr(sqr(-p));
         x2:=floattostr(-b/2)+'-'+'i'+floattostr(sqr(-p));
         edit4.Text:=x1;
         edit5.Text:=x2;
         except
           showmessage('溢出');
         end;
      end;
end;

Answer 7

呵呵sqr 和 sqrt 的区别，还不好发现呀！

Answer 8

改了以后的（其实什么都没改）var
a,b,c:integer;
p:real;
x1,x2:string;
begin
  a:=strtoint(edit1.Text);
  b:=strtoint(edit2.Text);
  c:=strtoint(edit3.Text);
  p:=b*b-4*a*c;
  edit6.Text:=floattostr(p);   if p>=0 then
    begin
      try
        showmessage(floattostr(sqrt(p)));
        x1:=floattostr((-b+sqrt(p))/2/a);
        x2:=floattostr((-b-sqrt(p))/2/a);
         edit4.Text:=x1;
         edit5.Text:=x2;
         except
           showmessage('溢出');
     end
     end
    else if p<0 then
     begin
       try
         x1:=floattostr(-b/2)+'+'+'i'+floattostr(sqrt(-p));
         x2:=floattostr(-b/2)+'-'+'i'+floattostr(sqrt(-p));
         edit4.Text:=x1;
         edit5.Text:=x2;
         except
           showmessage('溢出');
         end;
      end;
end;