26.

uses crt;

var a,b: integer;

begin

clrscr;

readln(a,b);

write('Dine tich=',a*b);

readln

end.

27.

uses crt;

begin

clrscr;

writeln('Ho: Nguyen');

writeln('Ten: Dieu');

writeln('Lop 8A');

readln

end.

28.

uses crt;

var x,y: integer;

begin

clrscr;

readln(x,y);

writeln('KQ=',x+x*x*y-x*y*y+y);

readln

end.

`26)`

uses crt ;
 var a,b : real ;
  begin
   clrscr ;
    write('nhap do dai 2 canh :') ;
     readln(a,b) ;
    writeln('Dien tich 2 canh la: ',(a*b):3:2);
     readln
      end.

`27)`

begin
  writeln ('Nguyen Thi Hien Dieu ');
  writeln ('Lop 8B');
end.

`28)`

uses crt ;
 var x,y : longint ;
  begin
   clrscr ;
    write('nhap x,y: ') ;
     readln(x,y) ;
    writeln('Gia tri cua bien thuc la : ',x+x*x*y-x*y*y+y) ;
     readln
      end.

$\text{Hình 1 bài 27, hình 2 bài 26, hình 3 bài 28}$