bạn không hiểu cách làm hay bạn có thắc mắc gì sao?

\(=\left(x+3\right)\left(x^2-3x+9\right)+\left(x+3\right)\left(x-9\right)\)
\(=\left(x+3\right)\left(x^2-3x+9+x-9\right) \)
\(=\left(x+3\right)\left(x^2-2x\right)\)

25. They are getting along with all their neighbors. (NEIGHBORHOOD)
26. The residents in this neighborhood are having a meeting. (RESIDE)
27. So far this restaurant has served the neighborhood for years. (SERVE)
28. Food in the market looks delicious. (DELICIOUS)
29. We must arrange a convenient time and place for the meeting. (CONVENIENCE)
30. My mother cooked a tasty dish last night. (TASTE)

The room is cleaned by the pupils every day/

1. entertainment
2. relatives
3. friendly
4. destruction
5. plentiful
6. unpleasant
7. polluted
8. permanently
9. boring/bored
10. accessible

1. Riding
2. farming
3. development
4. carefully

1. Pop music is more popular with young people than the elderly. (popular)
2. Which one is longer, Red River or Meking River? (long)
3. Harvest time is the busiest time of the year in my hometown. (busy)
4. My garden is colourful in spring when flowers bloom. (colour)
5. My grandmother lives in the city. She says it's noisier than my village. (noisy)
6. Who lives more happily, nomads or city dwllers? (nomadic)
7. Chilren in rural areas travel to shool farther than those in big cities. (far) 

A

'color
'passion
be'have
'children
pre'pare
re'peat
'purpose
po'lice
per'mission
com'puter
'million
per'fection
at'tend
'option
per'cent
be'come
'morning
'college
ar'rive
'famous
tele'vision
infor'mation
edu'cation
acti'vation
calcu'lation
cor'rection
a'doption
de'cision
ad'diction
adminis'tration
ab'straction
na'tion
i'talian
lo'gician
'indian
ca'nadian
mu'sician
elec'trician
bra'zilian
li'brarian
phát âm líu lưỡi :p

hm, câu 41. helping
             42. doing   
đều đúng nha!