2:

#include <bits/stdc++.h>

using namespace std;

int main()

{

int n,i,kt=0;

cin>>n;

for (int i=2; i*i<=n; i++)

if (n%i==0) kt=1;

if (kt==0) cout<<"YES";

else cout<<"NO";

}

program tamgiac;

uses crt;

var a,b,c: integer;

BEGIN

clrscr;

reapeat begin write ('nhap a = '); readln (a); end;

until a>0;

reapeat begin write ('nhap b = '); readln (b); end;

until b>0;

reapeat begin write ('nhap c = '); readln (c); end;

until c>0;

if (a*a=b*b+c*c) or (b*b=a*a+c*c) or (c*c=a*a+b*b)

then write ('3 canh ay la 3 canh cua tam giac vuong')

else ('3 canh ay khong la 3 canh cua tam giac vuong');

READLN

END.

Lời giải :

program hotrotinhoc ;

var a,b,c : integer ;

begin

write('nhap gia tri a'); readln(a);

write('nhap gia tri b'); readln(b);

write('nhap gia tri c'); readln(c);

If (a+b>c) or (a+c>b) or (b+c>a) then write('Chung la ba canh cua tam giac') else write('Chung khong phai la ba canh cua tam giac');

readln

end.

uses crt;

var a,b,c,p,s:real;

begin

clrscr;

repeat

write('Nhap a='); readln(a);

write('Nhap b=');c readln(b);

write('Nhap c='); readln(c);

until (a>0) and (b>0) and (c>0);

if (a+b>c) and (a+c>b) and (b+c>a) then 

begin

kt:=0;

if sqr(a)=sqr(b)+sqr(c) then kt:=1;

if sqr(b)=sqr(a)+sqr(c) then kt:=1;

if sqr(c)=sqr(a)+sqr(b) then kt:=1;

if kt=0 then writeln('Day khong la tam giac vuong')

else begin

              writeln('Day la ba canh trong mot tam giac vuong');

p:=(a+b+c)/2;

s:=sqrt(p*(p-a)*(p-b)*(p-c));

writeln('Dien tich tam giac vuong la: ',s:4:2);

end;

end

else writeln('Day khong la ba canh trong mot tam giac');

readln;

end.

b: 

#include <bits/stdc++.h>

using namespace std;

long long a,b,t;

int main()

{

cin>>a>>b;

t=a+b;

cout<<t;

return 0;

}

program chia_het;

uses crt;

var a,b:integer;

begin

writeln('Nhap so thu nhat');readln(a);

writeln('Nhap so thu hai');readln(b);

If (a mod b = 0) then writeln('chia het') else writeln('chia khong het');

readln

end.

uses crt;

var a:integer;

begin

clrscr;

write('Nhap a='); readln(a);

if a<0 then writeln(a,' la so am')

else if a>0 then writeln(a,' la so duong')

else writeln(a,' khong la so am cung khong la so duong');

readln;

end.

var A: integer;

begin

write('Nhap vao mot so A='); readln(A);

if A>0 then write('So A la so nguyen duong');

if A<0 then write('So A la so nguyen am');

If A=0 then write('So A khong la so nguyen am va khong la so nguyen duong');

readln;

end.