A=1/1*3+1/3*5+...+1/9*11+1/11*13

=1/2(1-1/3+1/3-1/5+...+1/11-1/13)

=1/2*12/13=6/13<B

1) `-3\sqrt13=-3\sqrt13`

`-9=-3\sqrt9`

`\sqrt13>\sqrt9`

`=> -3\sqrt13 < -3\sqrt9`

`=> -3\sqrt13 < 9`.

2) `\sqrt15 < \sqrt16`

`<=> \sqrt15-1 < \sqrt16-1`

`<=> \sqrt15-1 < 3 < \sqrt10`

`=> \sqrt15-1 <\sqrt10`

3) `5=4+1=\sqrt16+1`

`\sqrt8+1=\sqrt8+1`

`=> 5>\sqrt8+1`

1) \(-3\sqrt{13}=-\sqrt{117}< -\sqrt{81}=-9\)

3) Ta có: \(5^2=25=9+16\)

\(\left(2\sqrt{2}+1\right)^2=9+4\sqrt{2}\)

mà \(16>4\sqrt{2}\)

nên \(5>2\sqrt{2}+1\)

1) $-3\sqrt{13}=-\sqrt{117}<-\sqrt{81}=-9$

3) Ta có: ${}^{}=25=9+16$

${}^{}=9+4\sqrt{2}$

mà $16>4\sqrt{2}$

nên $5>2\sqrt{2}+1$

Ta có: `8^111 =(2^3 )^111 =2^(3.111)=2^333`

`4^170 =(2^2 )^170 =2^(2.170)=2^340`

Vì `333<340=>8^111 <4^170`

Ta có: `3^300 =3^(3.100)=(3^3 )^100=27^100`

`5^200 =5^(2.100)=(5^2 )^100 =25^100`

Vì `27>25=>3^300 >5^200`

a: 8^111=2^333

4^170=(2^2)^170=2^340

mà 333<340

nên 8^111<4^170

b: 3^300=(3^3)^100=27^100

(5^200)=(5^2)^100=25^100

mà 27>25

nên 3^300>5^200

sin30 <sin69

cos81<cos40

\(sin30^0< sin69^0\)

\(cos81^0< cos40^0\)

-Sin 30 < Sin 69

-Cos 81< Cos 40

Vì \(-\frac{13}{72}< 0\frac{1}{10000}\Rightarrow-\frac{13}{72}< \frac{1}{10000}\)

Vì \(-\frac{5299}{5199}< -1< -\frac{1963}{2017}\Rightarrow-\frac{5299}{5199}< -\frac{1963}{2017}\)

Ta có :\(-\frac{1111}{4444}=-\frac{1}{4}=-\frac{15}{60}\)

Vì\(-\frac{15}{61}>-\frac{15}{60}\Rightarrow-\frac{15}{61}>-\frac{1111}{4444}\)

1/ .quê hương tôi có 1 con sông xanh biếc

nương gương soi tóc những hàng tre

tâm hồn tôi là một buổi trưa hè 

tỏa nắng xuống lòng sông lấp loáng

=> Tâm hồn tôi là một buổi trưa hè =>  tâm hồn được so sánh với 1 buổi trưa hè nóng nực, cũng như tâm hồn của nhà thơ như cũng đang nồng cháy.

b)con đi trăm núi ngàn khe 

ko bằng muôn nỗi tái tê lòng bầm

con đi đánh giặc 10 năm

chưa bằng khó nhọc đời bầm 60

=> Cho thây sự vất vả gian lao, công ơn to lớn của người mẹ

c)anh đội viên mơ màng

như nằm trong giấc mộng

=> Phép ss ở đây miêu tả tình trạng nửa mơ nửa tỉnh của anh đội viên

Tham khảo:

a. "Quê hương tôi có con sông xanh biếc

Nước gương trong soi tóc những hàng tre

Tâm hồn tôi là một buổi trưa hè

Tỏa nắng xuống lòng sông lấp loáng."

b. "Con đi trăm núi ngàn khe

Chưa bằng muôn nỗi tái tê lòng bầm.

Con đi đánh giặc mười năm

Chưa bằng khó nhọc đời bầm sáu mươi."

c. "Anh đội viên mơ màng

Như nằm trong giấc mộng

Bóng Bác cao lồng lộng

Ấm hơn ngọn lửa hồng."

→Từ so sánh: in đậm

→Kiểu so sánh:

+Là, như: so sánh ngang bằng

+Chưa bằng, hơn: so sánh không ngang bằng

→Phép so sánh em thích:

"Con đi trăm núi ngàn khe

Chưa bằng muôn nỗi tái tê lòng bầm.

Con đi đánh giặc mười năm

Chưa bằng khó nhọc đời bầm sáu mươi."

→Tác dụng: làm rõ về nỗi khó nhọc của người mẹ và sự thương nhớ, biết ơn công lao của tác giả đối với mẹ.

Bài 2: 

\(A=\sqrt{26}+\sqrt{10}>\sqrt{25}+\sqrt{9}=5+3=8\)

\(B=\sqrt{64}=8\)

Do đó: A>B

1.Ta có:

\(A=\)\(\sqrt{13}+\sqrt{20}=\sqrt{13}+2\sqrt{5}\)

\(B=\)\(\sqrt{24}+\sqrt{19}=\sqrt{19}+2\sqrt{6}\)

So sánh ta thấy:

\(\sqrt{13}<\sqrt{19}\) ; \(2\sqrt{5}<2\sqrt{6}\)

Vậy A < B

`1)1/2:2/3 .... 2/3 : 1/2`

`=>1/2xx3/2 .... 2/3xx2`

`=>3/4 .... 4/3`

Vì `3/4 < 1` và `4/3>1` 

`=>3/4<4/3`

__

`4/7:2/5 ... 4/7 : 3/5`

`=>4/7xx5/2....4/7xx5/3`

`=>20/14...20/21`

`=>10/7...20/21`

Vì `10/7>1` và `20/21<1` 

`=>10/7>20/21`

__

`4/15:4/7....2/5xx10/3`

`=>4/15xx7/4...20/15`

`=>7/15...20/15`

Vì `7<20` nên `7/15<20/15`

__

`5/6...15/18-11/18`

`=>5/6...4/18`

Ta có : MSC : `18`

`5/6 = 15/18`

Vì `15>4` nên `5/6 > 4/18`

`2)2/3=(2xx6)/(3xx6)=12/18`

`7/9=(7xx7)/(9xx7)=49/63`

`6/5=(6xx3)/(5xx3)=18/15`

`2/3=(2xx5)/(3xx5)=10/15`

`5/9=(5xx5)/(9xx5)=25/45`

`49/56=(49:7)/(56:7)=7/8`

`6/8=(6xx7)/(8xx7)=42/56`

`2/9=(2xx7)/(9xx7)=14/63`

`49/56=(49:7)/(56:7)=7/8`

1. Hoa is shorter than Lan. -> Lan is higher then Hoa.

2. Ba is bigger than Nam. -> Nam is smaller than Ba.

3. This picture is more beautiful than that one. -> That picture is not as beautiful as this one.

4. Minh is more intelligent than Na. -> Na is not as intelligent as Minh

5. My bag is cheaper than yours. -> Your bag is more expensive than my bag.

6. No one in the group is taller than Trung. -> Trung is the tallest in the group.

7. Do you have a better television than this? -> Is this the best television you have?

8. My house is the oldest house on the street. -> No houses on the street is older than my house.

9. No other person in the town is so poor as him. -> He is the poorest in the town.

10. Have you got a cheaper carpet than this? Is this the cheapest carpet you have?

11. No one in the group is younger than her. -> She is the youngest in the group.

12. Tom is the best soccer player in the team. -> No one in the team play soccer better than Tom.

13. My sister is taller than any other student in the class. My sister is the tallest in the class.

14. This story is more interesting than any other story that I have ever read. -> This is the most interesting I have ever read.

15. No one in our class is taller than Nam. -> Nam is the tallest in our class.

16. His shoes are newer than mine. -> My shoes are older than his shoes.

17. Spring is cooler than summer. -> Summer is hotter than spring.

18. David is the fattest one in my family. -> No one in my family is fatter than David.

19. Susan isn’t as good at chemistry as Sarah. -> Sarah is better at chemistry than Susan.

20. Stone isn’t as hard as iron. -> Iron is harder than stone.

21. No other city in Viet Nam is so large as Ho Chi Minh City. -> Ho Chi Minh City is the largest in Viet Nam.

22. My brother isn’t so good at Math as his friend. -> My brother is worse at Math than his friend.

23. My mother is the best cook in the world. -> No mother in the world cook better than my mother.

24. He is the most helpful boy in my village. -> No one in my village is more helpful than him.

25. The black car is cheaper than the red car. -> The red car is more expensive than the black one.

26. He is the tallest boy in his class.          → No one in his class is taller than him.

27. This is the most interesting film of all.           → No other films are more interestig than this one.

28.    No cars in the world are more expensive than Japanese ones.→Japanese cars is the most expensive in the world.

29.    This exercise is easier than that one.                       → That exercise is not so easy as this one.

30.    He drives more carefully than Jack does.   → Jack drives carefulless than him does.

31.    No one in the group plays better than he.   → He can play the best in the group.

32.    No hotel in the city is as comfortable as this.→ This hotel is the most comfortable in the city

33.    Other oceans in the world aren’t as large as the Pacific one. → The Pacific Ocean is the largest in the world.

                                       Cho dạng đúng của từ trong ngoặc:

1. Ha Noi is ( small ) smaller than Ho Chi Minh, but Da Nang is ( small )the smallest of these three cities.

2. Which is ( big ) bigger Phong’s school or Hoa’s school?

3. My sister is four years ( old ) older than me.

4. The Amazon river is ( long ) longer than the Mekong river, but the Nile is (long)  the longest .in the world.

5. Food in the city is ( expensive ) more expensive than I think.

6. The streets in Hue are now ( narrow ) narrower than those in Hai Phong , but they are much ( clean ) the cleanest