Bài 1:Tính hợp lí

a)-12,5+17,55-3,5+2,45

b)0,175-(\(2\dfrac{1}{3}\)+0,175)

c)\(\dfrac{5}{13}\).\(\dfrac{-3}{10}\)+\(\dfrac{3}{10}\).\(\dfrac{-8}{13}\)+(-0,7)

Bài 2:Tìm x biết

a)x+\(\dfrac{2}{5}\)=2,4

b)2x-\(\dfrac{4}{5}\)=-1,5

c)11-(15+11)=x-(25-9)

Bài 3:Cho A=\(\dfrac{1}{2^2}\)+\(\dfrac{1}{3^2}\)+\(\dfrac{1}{4^2}\)+\(\dfrac{1}{5^2}\)+....+\(\dfrac{1}{100^2}\)

         Chứng tỏ A<1

Bài 1:Chứng tỏ rằng:B=\(\dfrac{1}{2^2}\)+\(\dfrac{1}{3^2}\)+\(\dfrac{1}{4^2}\)+\(\dfrac{1}{5^2}\)+\(\dfrac{1}{6^2}\)+\(\dfrac{1}{7^2}\)\(\dfrac{1}{8^2}\)<1

Bài 2:Chứng tỏ rằng:E=\(\dfrac{3}{4}\)+\(\dfrac{8}{9}\)+\(\dfrac{15}{16}\)+...+\(\dfrac{2499}{2500}\)<1

Bài 3:Chứng tỏ rằng:1<\(\dfrac{2011}{2020^2+1}\)+\(\dfrac{2021}{2020^2+2}\)+\(\dfrac{2021}{2020^3+3}\)+...+\(\dfrac{2021}{2020^3+2020}\)< 2

B=(1-\(\dfrac{1}{2^2}\))(1-\(\dfrac{1}{3^2}\))(1-\(\dfrac{1}{4^2}\))(1-\(\dfrac{1}{5^2}\))...(1-\(\dfrac{1}{99^2}\))(1-\(\dfrac{1}{100^2}\))

C=(\(\dfrac{1}{4}\)-1)(\(\dfrac{1}{9}\)-1)(\(\dfrac{1}{16}\)-1)...(\(\dfrac{1}{999}\)-1)

II.Use the conjunction at the end of the sentence to connect two simple sentences
1.We're watching a comedy.We're laughing happily.(so)
.................................................................................
2.Vy joined The Voice Kids.Her sister joined it,too.(and)
...........................................................................
3.The environment is polluted.Our health is getting worse.(Because)
........................................................................
4.My father always reads the newspaper in the morning. He always watches the TV news in the morning.(and)
................................................................

vẽ 4 đường thẳng ABCD cùng đi qua một điểm O.Vẽ đường thẳng M không đi qua điểm O cắt các đường thẳng ABCD lần lượt ABCD

1)3-(x+\(\dfrac{5}{7}\))=\(\dfrac{9}{21}\)

2)\(\dfrac{x}{2}\)+\(\dfrac{x}{5}\)=\(\dfrac{17}{10}\)

3)\(\dfrac{1}{2}\)x+\(\dfrac{1}{3}\)-1=3\(\dfrac{1}{3}\)

I.Use and,but or so to complete the sentences

 1.My brother likes football,_______he watches sports programmes every Sunday

2.I have a lot of homework,________I don't watch TV on weekdays

3.I usually watch the news,________I watch wildife programmes, too

4.My classmate is interested in films,______he never watches films on TV

5.My father usually comes home at six o'clock,________then he watches TV for an hour

6.The characters of the film are very nice,________the music doesn't sound very modern

7.Mr.Wealthy is very rich,________he never feels happy

8.Minh studies very hars,_______he always gets good grades

II.complete the following sentences with suitable question words

 1._________do you prefer-The Lion King or Tom and Jerry?
 2._________does this programme finish?

 3._________is the best actor in your country?

 4._________was the weather like last Sunday?

 5._________don't you like this comedy?

1)2x+(-15)-9=-24

2)(x-34):20=-12

3)13-2x=-25-(31-25)

4)250:(x-5)=64-14

5)12:(x+5)=17+(-23)

6)6²+64:(x-1)=32

7)3.(x+5)-x-11=24

14)-19+4.(2-x)+x=25

15)17-{-x+[-x-(-x)]}=-16

Bài 1: Tính

1)-(-8)-9+10+(-14)+(+12)

2)-14+(-13)-(-9)-5

3)-9+17-18+12-23

4)-12+(+14)-17+(-3)

5)-(-17)-(+15)+18-20

6)11-15+13-17+8-4

Bài 8: Bỏ ngoặc rồi tính

1)(-5)+(-18)-(+9)+(+3)

2)-11-(-15)+(-13)-(+9)+(-5)

3)(-4)-(-8)+(-15)+(-10)

4)-(-4)-(-12)-(+5)+19

5)-(+7)-(-12)+(-9)+(+10)

6)-(28-30+4)

7)16-(-3)+(-5)-(+7)+12

8)13-(17-15-3)+(-4+8-9)