Tính :

a) (26−6).(−4)+31(−7−13)

=20.(-4)+31.(-20)

=-20(4+31)

=(-20).35

=-700

b) (−18).(55−24)−28.(44−68)

=(-18). 31- 28. (-24)

=6.(-3).31-28.(-4).6

=6. (-93)+ 112.6

=6.(-93+112)=114

1. when being a child, she received a good.....education.......(education)

2. walking is a fun, easy and ......inexpensive....activity(expensive)

3. A balanced diet alone is not enough for a healthy.......lifestyle...(life)

4. That woman is very pleasant, but her younger sister is a little ..unfriendly.. . (friend)

5. Ha likes to wear .....colourful...... Clothes(colour)

6. The teacher....encouranges..... The students to study harder( courage)

7. The students enjoy......different........ activities after school hours(differ)

8. Some students are following the...librarian......to the video room(library)

9. The post arrives...regularly.... At eight in the mỏning(regular)

10. Do your classes start....earlier.....or later ?(early)

1) well-> f)mannered => well mannered : lịch sự

2) bad-> b) tempered => bad tempered: nóng tính

3)old-> e) fashioned => old fashioned : cổ hủ, lỗi thời

4)absent->b) minded => absent minded : vắng mặt

5) short-> c)sighted => short sighted : cận thị

6) red-> a) haired => red haired : tóc đỏ

dien tich mot hinh chu nhat : (385-5x5):2=180 cm        

canh hinh vuong ban dau: 180:5+5=41cm 

chu vi hinh vuong ban dau: 41x4=164cm

A=3^100-3^99+3^98-3^97+.................+3^2-3+1
3A = 3^101-3^100+3^99-3^98+3^97-3^96+...........................-3^2+3
3A + A = 3¹⁰¹+1
4A = 3¹⁰¹ + 1
A = \(\frac{3^{101}+1}{4}\)