- Thuật toán RSA sử dụng khóa công khai và khóa bí mật để mã hóa và giải mã dữ liệu. Việc sử dụng khóa công khai và khóa bí mật giúp đảm bảo tính bảo mật và xác thực của thông tin được truyền tải.

- Độ dài khóa của thuật toán RSA là rất lớn, thường là từ 1024 bit đến 4096 bit, giúp làm tăng tính bảo mật của thuật toán.

- Các thuật toán khác trong hệ mật mã RSA cũng rất an toàn và đáng tin cậy, giúp nâng cao tính bảo mật của thuật toán.

program TongCacSoChiaHetChoBa;

var

     n, i, sum: integer;

begin

repeat

          Write('Nhap so nguyen n (3 <= n <= 50): ');

          Readln(n);

     until (n >= 3) and (n <= 50);

     sum := 0;

     for i := 3 to n do

     begin

          if i mod 3 = 0 then

          sum := sum + i;

     end;

     WriteLn('Tong cac so chia het cho 3 trong khoang tu 3 den ', n, ': ', sum);

     ReadLn;

end.

with open("a.txt", "r") as f:

     numbers = list(map(int, f.readline().split()))

product = 1

for number in numbers:

     product *= number

print("Tích các số trong file a.txt là:", product)

#include<iostream>

#include<cmath>

using namespace std;

int main() {

       double x, y, z, t;

       double pi = acos(-1.0);

       double a, b, c, d;

       cin >> x >> y >> z >> t;

       double alpha = x * pi / 180, beta = y * pi / 180;

       double gamma = z * pi / 180, delta = t * pi / 180;

       double distance = cos(alpha) + cos(beta) + cos(gamma) + cos(delta);

       if (distance == 2) {

              cout << "YES" << endl;

       } else {

              cout << "NO" << endl;

       }

       return 0;

}

program dem_so_am_duong_0;

uses crt;

var B: array[1..100] of integer;

      i, n, count_am, count_duong, count_0: integer;

begin

      write('Nhap n: ');

      readln(n);

      for i :=1 to n do

      begin

            write('Nhap phan tu B[' , i, ']: ');

            readln(B[i]);

      end;

      count_am :=0;

      count_duong :=0;

      count_0 :=0;

      for i :=1 to n do

      begin

            if B[i] <  0 then 

                  count_am := count_am + 1

            else if B[i] >  0 then 

                  count_duong := count_duong + 1

            else

                  count_0 := count_0 + 1;

      end;

      write('So phan tu am trong mang: ', count_am);

      write('So phan tu duong trong mang: ', count_duong);

      write('So phan tu bang 0 trong mang: ', count_0);

      readln;

end.

B.CLOCKS

a)  

\(\dfrac{1}{2}=0,5;\dfrac{3}{4}=0,75;\dfrac{7}{5}=1,4;\dfrac{9}{8}=1,125;\dfrac{26}{25}=1,04;\dfrac{120}{125}=0,96\)

b) 

\(\dfrac{15}{25}=0,6;\dfrac{75}{25}=3;\dfrac{90}{300}=0,3;\dfrac{27}{36}=0,75;\dfrac{51}{85}=0,6\)

a)  \(\dfrac{2}{5}-x=1,2\times\dfrac{2}{5}\)

     \(\dfrac{2}{5}-x=\dfrac{12}{25}\)  

             \(x=\dfrac{-2}{25}\)

b)  \(0,3-\dfrac{2}{5y}=-1\)

     \(\dfrac{1,5y}{5y}-\dfrac{2}{5y}=-\dfrac{5y}{5y}\)

→  \(1,5y-2=-5y\)

       \(6,5y=2\)

            \(y=\dfrac{4}{13}\)

    In today's digital age, screens have become an integral part of our daily lives. However, excessive screen time can have some negative impacts on our health, particularly for teenagers. In my opinion, it is important to limit teenagers' screen time. Firstly, prolonged exposure to screens has been linked to a variety of health problems such as obesity, poor eyesight, and insomnia. Spending excessive amounts of time in front of screens can also cause headaches, neck and back pain, and postural problems. Limiting teenagers' screen time can help ensure that they get enough physical activity, fresh air, and quality sleep that their growing bodies need. Secondly, excessive screen time can negatively impact teenagers' mental health. It can lead to feelings of isolation, anxiety, depression, and even addiction. Social media platforms, for instance, can create unrealistic expectations for youth, leaving many feeling inferior and depressed. To combat this, teenagers should learn to moderate their Internet and screen usage, and pursue more meaningful and fulfilling activities. Thirdly, screen time can affect teenagers' cognitive development. The brain of a teenager is still developing, and research shows that excessive screen time can impede brain development that affects cognitive skills such as attention span, memory, and problem solving. In contrast, spending more time reading, interacting face-to-face with peers, and engaging in outdoor activities can help teenagers build positive cognitive skills. In conclusion, while screens are useful tools, they should be used in moderation, especially for teenagers. Limiting their screen time can have positive effects on their physical, mental, and emotional well-being. Parents and guardians should encourage teenagers to find other activities that they enjoy besides screens such as sports, arts, traveling, and socializing with peers. By doing so, teenagers can strike a healthy balance between screen time and other activities, leading to a healthier and happier life.

a)  Ta có:   \(A=\dfrac{x}{x+2}-\dfrac{2x}{x-2}+\dfrac{x^2+12}{x^2-4}\left(x\ne\pm2\right)\)

\(A=\dfrac{x\left(x-2\right)-2x\left(x+2\right)+x^2+12}{\left(x-2\right)\left(x+2\right)}\)

\(A=\dfrac{x^2-2x-2x^2-4x+x^2+12}{\left(x-2\right)\left(x+2\right)}\)

\(A=\dfrac{-6\left(x-2\right)}{\left(x-2\right)\left(x+2\right)}\)

\(A=\dfrac{-6}{x+2}\)

b) Để A có giá trị nguyên thì \(x+2\inƯ\left(6\right)\)

Mà \(Ư\left(6\right)=\left\{\pm1;\pm2;\pm3;\pm6\right\}\)

Từ đó, ta có:

\(x+1=1\Leftrightarrow x=0\) ( nhận )

\(x+1=-1\Leftrightarrow x=-2\)  ( loại )

\(x+1=2\Rightarrow x=1\) ( nhận )

\(x+1=-2\Rightarrow x=-3\) ( nhận )

\(x+1=3\Rightarrow x=2\) ( loại )

\(x+1=-3\Rightarrow x=-4\) ( nhận )

\(x+1=6\Rightarrow x=5\) ( nhận )

\(x+1=-6\Rightarrow x=-7\) ( nhận )

Vậy để A nhận giá trị nguyên thì \(x\in\left\{-7;-4;-3;0;1;5\right\}\)