Bài 1:

program tong_binh_phuong;

uses crt;

var A:array[1..1000] of integer;

      n,i:integer;

      t:longint;

begin

       clrscr;

       write('Nhap so luong phan tu: ');  readln(n);

       t:=0;

       for i:=1 to n do

              begin

                     write('Nhap A[',i,']= ');  readln(A[i]);

                     t:=t+A[i]*A[i];

              end;

       write('Tong binh phuong cac so trong mang la: ',t);

       readln;

end.

Bài 2:

program dem_k;

uses crt;

var s:string;

      k:char;

      i,d:byte;

begin

       clrscr;

       write('Nhap xau: ');  readln(s);

       write('Nhap k: ');  readln(k);

       d:=0;

       for i:=1 to length(s) do

              if s[i]=k then d:=d+1;

       write('So lan xuat hien cua ',k,' la: ',d);

       readln;

end.

b1 

program pascal; 

uses crt;

var A:array[1..300] of integer;

i,n,tong:word;

begin

clrscr;

writeln('nhap n = ');

readln(n);

for i:=1 to n do 

begin

writeln('nhap phan tu thu ' , i ,' = ' );

readln(a[i]);

end;

tong:=0;

for i:=1 to n do 

tong:=tong+sqr(a[i]);

writeln('tong binh phuong la ',tong);

readln

end.

b2 

program pascal;

uses crt; 

var s:string;

k:char;

dem,i:byte;

begin

clrscr;

writeln('nhap xau ');

readln(s);

writeln('nhap k ');

readln(k):

dem:=0;

for i:=1 to length(s) do

if s[i] = 'k' then

dem:=dem+1;

writeln('so lan xuat hien k trong xau la ',dem);

readln

end.