Bài 1:

Program Bai1;
uses crt;
var a,b:integer;

BEGIN
    Write('Nhap a: '); readln(a);
    Write('Nhap b: '); readln(b);
    Write('Ket Qua: ',a/b:1:5);
    readln;
END.

Bài 2:

Program Bai1;
uses crt;
var n,sum:integer;

BEGIN
    sum:=0;
    Write('Nhap N: '); readln(n);
    for i:= 1 to n do sum := sum+i;
    Write('Ket Qua: ',sum);
    readln;
END.

Bài 3:

Program Bai3;
Uses crt;
Var a,b,c,d,x,x1,x2:real;
Begin
Write('Nhap he so a=');readln(a);
Write('Nhap he so b=');readln(b);
Write('Nhap he so c=');readln(c);
If a=0 then
   If b=0 then
       If c=0 then
Writeln('Phuong trinh co vo so nghiem')
       Else
Writeln('Phuong trinh vo nghiem')
   Else
Writeln('Phuong trinh co mot nghiem: x=',-c/b:4:2)
Else
Begin
d:=b*b-4*a*c;
If d=0 then
Writeln('Phuong trinh co nghiem kep: x=',-b/(2*a):4:2)
Else
If d<0 then
Writeln('Phuong trinh vo nghiem')
Else
Begin
x1:= (-b+sqrt(d))/(2*a);
x2:= (-b-sqrt(d))/(2*a);
Write('Phuong trinh co hai nghiem: ‘);
Writeln(‘ x1=',x1:4:2,' va x2=',x2:4:2);
End;
End;
Readln;
End.