Rút gọn các biểu thức sau:

a) (x² - 1)³ - (x⁴ + x² + 1) (x² - 1)

b) (x⁴ - 3x² +9) (x² + 3) - (3 + x²)³

c) (x - 3)³ - (x - 3) (x² + 3x + 9) + 6 (x + 1)²

Tính:

(x²−1/3).(x⁴+1/3x²+1/9)

FIl in the blank with ''used to/ am used to''.

1. I. . .going to school alone.

2. My brother. . .go to school in the afternoon.

Yesterday was Sunday. We didn’t work. We all stayed at home. In the morning my father planted some trees and then watered them. He always likes doing the gardening. My mother tidied our house then cooked a good lunch. I watched TV then helped my mother with the housework. I cleaned the floor and dusted the furniture. My brother listened to music. In the afternoon one of my father’s friend visited us. They talked and played chess together. My brother pained a nice picture. I learned my lessons.We were busy all day but everybody was very happy.

1. Why didn't they work yesterday?

2. What did her mother do?

3. Did her brother listen to music?

4. Were they unhappy on that day?