Ta có : 5=5+0
=4+1
=3+2
=> ta có các số : 50;41;14;32;23.
Vậy tập hợp các số tự nhiên có 2 chữ số mà tổng các chữ số của mỗi số đó bằng 5 có số phần tử là 5
5 đúng 100% 14,41,50,23,32 k tôi đi các bạn
5 phần tử, có thể làm theo cách liệt kê hoặc cách khác, muốn biết thì tích nha
có 5 phần tử đúng 1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000%
bạn Dũng kia sao mà viết dài thế. đúng là ko biết mệt!!!!!!!