Câu 3. Tính nhanh a) A = 392 + 78 · 61 + 612; b) B = 2,83 · 5,68 − 2,83 · 4,68 + 1,17 · 5,68 − 1,17 · 4,68; c) C = 202 + 182 + 162 + · · · + 42 + 22 − (192 + 172 + · · · + 32 + 12)

Các câu hỏi liên quan

II. Writing 1. Luke / playing/ like/ Does/ sports/? →______________________________________________________________ 2. Anything else/ wants / he/ Is there/ to try/ ? →______________________________________________________________ 3. you/ enjoy/ Are there/ other activities/ doing/ any/ ? →______________________________________________________________ 4. Finishes/ at/ My / art class/ 10 a.m/ usually/./ →______________________________________________________________ 5. the quiz show/ does/ what time/ start/ ? →______________________________________________________________ 6. Do/ play/ you/ want/ to/ after/ table tennis/ school/ ? →______________________________________________________________ 7. Let’s/ in / the/ park/ of/ meet/ front/ ./ →______________________________________________________________ 8. What/ you/ do/ chores/ have/ do/ to/ ? →______________________________________________________________ 9. daily/ My/ begins/ routine/ 6 a.m / at/ . →______________________________________________________________ 10. Nam/ look after/ helps/ his brother/every night/ his mom/. →______________________________________________________________ 11. I / the bus/ because/ take/ it’s too/ to walk/ far/ to my school/. →______________________________________________________________ 12. have / collect/ Tim/ to/ drink/ to/ clean water/. →______________________________________________________________ 13. My mother asks me to water plants in the garden. → I have ________________________________________________________ 14. Nam’s mom asks him to wash the dishes after dinner. → Nam has_______________________________________________________ 15. Do/ to go/ want/ on/ mountain biking/ Saturday morning/? →______________________________________________________________