a. P+Q = x²y+x³+3+x³+xy²-xy-6

P+Q = x²y+x³+x³+xy²-xy+3-6

P+Q = x²y+2x³+xy²-xy-3

Còn câu b bị lỗi đấy bạn.

1. to/energy/Turn/save/the lights/off/leaving/the/before/room

=> Turn off the lights before leaving the room to save energy.

Câu này thừa "end" đó bạn.

2. poor/in/the/people/don't/slum,/live/they?/Most/of

=> Most of poor people live in the slum, don't they?

P\(\left(\dfrac{-1}{4}\right)\)= 2. \(\left(\dfrac{-1}{4}\right)\) + \(\dfrac{1}{2}\)

= \(\dfrac{-1}{2}\) + \(\dfrac{1}{2}\)

= 0

2. The cafeteria is empty so they don't have to wait long.

Dịch: Quán ăn tự phục vụ thì vắng khách vì vậy họ không phải chời lâu.