Pascal: 

Câu 19;

Program ViDu;

Uses crt;

n,i,s1,s2,t:real;

kq:string;

BEGIN

Readln(n);

For i:= 1 to n do 

begin

t:=sqr(i);

s1:=s1+t;

end;

s2:=(n*(n+1)*(2*n+1))/6

if s1 = s2 then kq := 'Dung' else kq := 'Sai';

Writeln('Bieu thuc da cho voi n= ',n:1:0,' la ', kq );

readln; 

END.

Câu 20;

Program ViDu;

Uses crt;

n,i,s1,s2,t:real;

kq:string;

BEGIN

clrscr;

readln(n);

for i: = 1 to n do begin

t := i *i*i;

s1:=s1+t;

end;

s:=0;

for i:= 1 to n do begin

s2:=s2+i;

end;

s2:=sqr(s2);

if s1 = s2 then kq:='dung' else kq:='sai';

Writeln('Bieu thuc da cho voi n= ', n:1:0, 'la ', kq);

readln;

END.

Pỵthon:

Câu 19

n=int(input())

i = 1

s1 = 0

t = 0

while (i <= n):

       t = i**2

       s1 = s1 +t

        i += 1

s2 = ((n**2)*(n+1)*(2*n+1))/6

if s1 == s2:

      print('Bieu thuc da cho dung voi n= ' + str(n))

else:

     print('Bieu thuc da cho sai voi n = ' + str(n))

Câu 20

n=int(input())

i = 1

s1 = 0

t = 0

while (i <= n):

       t = i**3

       s1 = s1 +t

        i += 1

i = 1

s2 = 0

while (i <= n):

     s2 = s2 + i

     i+=1

s2 = s2**2

if s1 == s2:

      print('Bieu thuc da cho dung voi n= ' + str(n))

else:

     print('Bieu thuc da cho sai voi n = ' + str(n))

19.

uses crt;
var f:text; i,n:longint; s1,s2:real;
begin
clrscr;
   write('N=');readln(n);
   for i:=1 to n do s1:=s1+i*i;
   s2:=(n*(n+1)*(2*n+1))/6;
   writeln(s1=s2);
readln
end.

20. 

uses crt;
var f:text; i,n:longint; s1,s2:real;
begin
clrscr;
   write('N=');readln(n);
   for i:=1 to n do 
      begin 
         s1:=s1+i*i*i;
         s2:=s2+i;
      end;
   s2:=s2*s2;
   writeln(s1=s2);
readln
end.