8. Không làm phép tính, xét xem các số sau là số nguyên tố hay hợp số: a) A = 1.3.5.7.9 + 20; b) B = 21.22.23-6.7.8.

Các câu hỏi liên quan

Do you have a special hobby? Write an email (80-100 words) to your pen-friend, and tell him/her about it. You should base on the suggestions below: - What is your hobby? - When did you start it? - What do you do in your hobby? - Who do you like doing it with? - How much do you like doing it?/ How do you feel when you do it? - Why do you like doing it? - What will you do with your hobby in the future? Dear ........................, .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... Love, ...........................(Your signature)