квадратное уравнение

program ср1;

uses
    System.SysUtils;

var
    a, b, c, d, x, x1, x2: real;

begin
    a := 0;
    b := 0;
    c := 0;
    x := 0;
    x1 := 0;
    x2 := 0;
    writeln('a, b, c');
    readln(a, b, c);
    d := b * b - 4 * a * c;
    if (a = 0) then
        writeln('no')
    else if (d < 0) then
        writeln('no')
    else if (d = 0) then
    begin
        x := -b / (2 * a);
        writeln('x =', x);
    end
    else
    begin
        x1 := (-b + sqrt(d)) / (2 * a);
        x2 := (-b - sqrt(d)) / (2 * a);
        writeln('x1 =', x1);
        writeln('x2 =', x2);
    end;
    readln;

end.