c++:

c++:

#include <iostream>

using namespace std;

int main(){

int y;

cin >> y;

int i = 1;

int luythua = 1;

while(i<=y){

luythua = luythua *i;

i = i+1;

}

cout << luythua;

}

Xét n = 5k;

=> 3n+2 = 15k + 2 (không chia hết cho 5)

xét n = 5k+1:

=> 3n+2 =15k+5(thỏa mãn)
Xét n = 5k+2:

=> 3n + 2 = 15k + 8 (không chia hết cho 5)
Xét n = 5k+3:

=> 3n+2 = 15k+11(không chia hết)
Xét n = 5k+4:
=> 3n+2 = 15k + 14(không chia hết)
Đáp số: n = 5k+1(k thuộc tập hợp N)

On my first day at school, I was very excited as I was not going to be a primary schooler but a secondary schooler. I was very happy as it was very easy to make friends and the teacher's were very nice and friendly. Friend's were playful and jolly. Not only that but the food there was awesome. The food was filled with wonderful flavours. The classroom decorations was nice and it was very clean. The entrance was also welcoming. I hope that I will make lot's of friends in school too!
 

Tham khảo nhá :)

Gọi số bi xanh là: a;

gọi số bi vàng là:b

gọi số bi đỏ là:c

Ta có: a = b+c;

b = (a+c)/5 = (b+2c)/5

=> b = 1/5 *b + 2/5*c

=> 4/5b = 2/5c

=> 2/5b = 1/5c

=> 2b = c;

=> a = 2b +b = 3b
Lại có: a+b+c = 48

=> 3b + 2b + b = 48

=> 6b = 48

=> b = 8

=> a = 8*3 = 24

=> c = 8*2 = 16;

Đáp số: đỏ: 16 viên

xanh: 24 viên

vàng: 8 viên