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;

}

#include <bits/stdc++.h>

using namespace std;

long long a,b;

int main()

{

cin>>a>>b;

cout<<fixed<<setprecision(2)<<1/(a*1.0+b*1.0);

return 0;

}

#incude <bits/stdc++.h>

using namespace std;

long long x,y;

int main()

{

cin>>x>>y;

cout<<x*x+2*y+1;

return 0;

}

Program HOC24;

var t: longint;

a,b: integer;

function gt(x: integer): longint;

var i: integer; tich: longint;

begin

tich:=1;

for i:=1 to n tich:=tich*i;

gt:=tich;

end;

begin

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

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

t:=gt(a)+gt(b)+gt(a-b);

write('T = ',t);

readln

end.

\(A=\dfrac{5x^2}{x^2}-\dfrac{x}{x^2}+\dfrac{1}{x^2}=\dfrac{1}{x^2}-\dfrac{1}{x}+5=\left(\dfrac{1}{x^2}-\dfrac{1}{x}+\dfrac{1}{4}\right)+\dfrac{19}{4}=\left(\dfrac{1}{x}-\dfrac{1}{2}\right)^2+\dfrac{19}{4}\ge\dfrac{19}{4}\)

\(A_{min}=\dfrac{19}{4}\) khi \(\dfrac{1}{x}=\dfrac{1}{2}\Rightarrow x=2\)

`4/9xx13/3-4/3xx40/9`

`=4/9xx13/3-4/9xx40/3`

`=4/9xx(13/3-40/3)`

`=4/9xx(-9)`

`=-4`

Free time - Answer #5:

`B=4/9 . 13/3 - 4/3 . 40/9`

`B = 4/9 (13/3 - 40/9)`

`B = 4/9 (39/9 - 40/9)`

`B = 4/9 . (-1/9)`

`B = -4/81`

uses crt;

var x,y:integer;

begin

clrscr;

readln(x,y);

writeln(2*x*x+y);

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.