bạn bổ sung đoạn sau nhau : 
        end; 

readld

END. 

uses crt;
var delta:extended;
        a,b,c:longint;
{---Vo-nghiem---}
procedure delta_am;
begin
        write('PT vo nghiem');
end;
{---Co-nghiem-kep---}
procedure delta_khong;
begin
        write('PT co nghiem kep: x1=x2=',-b/(2*a):0:2);
end;
{---Co-2-nghiem-phan-biet---}
procedure delta_2;
begin
        write('PT co 2 nghiem phan biet: x1=',(-b+sqrt(delta))/(2*a):0:2,'; x2=',(-b-sqrt(delta))/(2*a):0:2);
end;
{---Chuong-trinh-chinh---}
BEGIN
        clrscr;
        write('Nhap a,b,c: '); readln(a,b,c);
        delta:=b*b-4*a*c;
        if delta<0 then delta_am
        else if delta=0 then delta_khong
        else delta_2;
        readln;
END.