Bài 2: 

#include <bits/stdc++.h>;

using namespace std;

int main();

{

long m,n;

cout<<"Nhap m="; cin>>m;

cout<<"Nhap n="; cin>>n;

cout<<m*n-2;

return 0;

}

Program HOC24;

var a,b: integer;

D: longint;

begin

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

write('Nhap b: '); readln(b);

D:=2*(a+b);

write('D = ',D);

readln

end.

Câu 2:

Program nii;

Uses crt;

Var a,b,c,A:integer;

Begin

Write ('nhap a');

Readln (a);

Write ('nhap b');

Readln (b);

Write ('nhap c');

Readln (c);

A:=a;

If A<b then A:=b;

If A<c then A:=c;

Write ('Ket qua',A);

Readln;

End.

Câu 1

Program ntg;

Uses crt;

Var A,x,y:integer;

Begin

Write ('nhap x');

Readln (x);

Write ('nhap y');

Readln ('y');

A:=x+y;

Write ('Ket qua',A);

Readln;

End.

Câu 2: 

uses crt;

var a,b,c,max:integer;

begin

clrscr;

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

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

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

max:=a;

if max<b then max:=b;

if max<c then max:=c;

writeln('So lon nhat trong 3 so la: ',max);

readln;

end.

program tinh;

uses crt;

var a;b:integer;

   C:real;

begin

  clrscr;

write('ban hay nhap so nguyen a,a='); read(a);

write('ban hay nhap so nguyen b,b='); read(b);

C=a*b/2;

write('gia tri bieu thuc C la,C=',C);

delay(5000);

end.

Câu 3: 

#include <bits/stdc++.h>

using namepsace std;

double a,b,c,p,s;

int main()

{

cin>>a>>b>>c;

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

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

cout<<fixed<<setprecision(2)<<s;

return 0;

}

Câu 3: 

#include <bits/stdc++.h>

using namepsace std;

double a,b,c,p,s;

int main()

{

cin>>a>>b>>c;

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

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

cout<<fixed<<setprecision(2)<<s;

return 0;

}