3) Mik k bt dung k nhưng mình chạy thử thì chạy được!
Program hoandoi; Var x,y,z:integer; Begin Writeln(x,'',y);Read(x,y); z:=x; x:=y; y:=z; Writeln(x,'',y); Readln; End.
4)
Program Baitap; Const So_PI = 3.14; Var R:Interger; S:Real; Begin Write('Nhap ban kinh hinh tron R=: ');readln(R); S:=So_PI*R*R; Write('Dien tich hinh tron la: ',S);
