1) |x| \(\le\) 3 Mà |x| \(\ge\) 0 và x nguyên nên |x| = 0; 1; 2; 3

=> x = -3; - 2; -1; 0 ; 1; 2; 3

Tổng các số nguyên x là:  (- 3 + 3) + (-2 + 2) + (-1 + 1) + 0 = 0

2) A = (1 - 2) + (3 - 4) + (5 - 6) + ...+ (2015 - 2016)

= (-1) + (-1) + ...+ (-1)  ( Có 2016 số nên có 2016 : 2 = 1008 cặp => có 1008 số -1)

= (-1).1008 = -1008

1 I played football last Sunday.

2 My mother made two cakes four days ago.

3 Tyler visited his grandmother last month.

4 Joni went to the zoo five days ago.

5 We had fun yesterday.

6 My father didn't at the office the day before yesterday.

1 How much does this book cost?

2 Let's go to the cinema