Verified answer

var

 a, b, c, D: real;

begin

 write('A= ');readln(a);

 write('B= ');readln(b);

 write('C= ');readln(c);

 D := b * b - 4 * a * c;

 if D < 0 then

   writeln('Нет корней')

 else

   if D = 0 then

     writeln('x1=', -b / (2 * a))

   else

     if D > 0 then  

       begin

         writeln('x1= ', (-b - sqrt(d)) / (2 * a));

         writeln('x2= ', (-b + sqrt(d)) / (2 * a));

       end;

end.