5²⁵⁵<2⁵⁷⁹

Ta có: \(B=20142015^2=\left(20142014+1\right)\left(20142016-1\right)=20142014.20142016+20142016-20142014-1=20142014.20142016-1< 20142014.20142016\)

\(\Rightarrow B< A\)

1.They are( talk) talking to their teacher.

2.there are thirty-six(class) classes in out school.

\(A=\left(x+2\right)^3+\left(x-2\right)^3-2x\left(x^2+12\right)\)

\(=\left(x+2\right)^3+\left(x-2\right)^3-2x^3-24x\)

\(=x^3+6x^2+12x+8+x^3-6x^2+12x-8-2x^3-24x\)

\(=\left(x^3+x^3-2x^3\right)+\left(6x^2-6x^2\right)+\left(12x+12x-24x\right)+\left(8-8\right)\)

\(=0\)

Does your class have thirty students ?
Are there thirty students in your class ?
How much does a bowl of noodles cost ?
How much is a bowl of noodles ?
He often walks to school 
He often goes to school on foot.
Mr Brown is has a daughter , Hoa 
Mr. Brown is Hoa's farther.
What is the length of this river ?
How long is the river..?
What is the price of a cake and an orange ?
How many do a cake and an orange cost?
That book belongs to Nam 
That is Nam's book

We must be ...careful...when we cross the road.      (CARE) 
There are a lot of ...beautiful.......mountains in Viet Nam     ( BEAUTY)
I'm Vietnamese . What's your ......nationality.........?    (NATION)
This is the ..tallest.....building in our town .     (TALL)
This tree has a lot of green .....leaves .( LEAF) 
I don't like.............sunny.......weather  (SUN) 
Mai's sister is a .............singer................. ( SING )
His .....teeth.........are small and white (  TOOTH )
It's very .............noisy.............in the city (NOISE)

a, Ta có: \(\frac{x}{4}=\frac{y}{3}=\frac{z}{9}\Rightarrow\frac{x}{4}=\frac{3y}{9}=\frac{4z}{36}\)

\(\Rightarrow\frac{x}{4}=\frac{3y}{9}=\frac{4z}{36}=\frac{x-3y+4z}{4-9+36}=\frac{62}{31}=2\)

\(\Rightarrow x=2.4=8\)

\(\Rightarrow y=2.3=6\)

\(\Rightarrow z=2.9=18\)

b, Ta có: \(\frac{x}{y}=\frac{10}{9}\Rightarrow\frac{x}{10}=\frac{y}{9}\)

\(\frac{y}{z}=\frac{3}{4}\Rightarrow\frac{y}{3}=\frac{z}{4}\Rightarrow\frac{y}{9}=\frac{z}{12}\)

\(\Rightarrow\frac{x}{10}=\frac{y}{9}=\frac{z}{12}=\frac{x-y+z}{10-9+12}=\frac{78}{13}=6\)

\(\Rightarrow x=6.10=60\)

\(\Rightarrow y=6.9=54\)

\(\Rightarrow z=6.12=72\)

c, Ta có: \(\frac{x}{3}=\frac{y}{4}\Rightarrow\frac{x}{9}=\frac{y}{12}\)

\(\frac{y}{3}=\frac{z}{5}\Rightarrow\frac{y}{12}=\frac{z}{20}\)

\(\Rightarrow\frac{x}{9}=\frac{y}{12}=\frac{z}{20}\Rightarrow\frac{2x}{18}=\frac{3y}{36}=\frac{z}{20}\)

\(\Rightarrow\frac{2x}{18}=\frac{3y}{36}=\frac{z}{20}=\frac{2x-3y+z}{18-36+20}=\frac{6}{2}=3\)

\(\Rightarrow x=3.9=27\)

\(\Rightarrow y=3.12=36\)

\(\Rightarrow z=3.20=60\)

1. I'm very hungry. (What/ you/ eat?)

-> What are you going to eat? 

2. We're going to the movies.(What/ you/ see?)

-> What are you going to see?

3. My brother's going to university in Septemmber. (What/ he/ study?)

-> What is he going to study?

4. My grandparents are coming for dinner tonight. (What/ you/ cook?)

-> What are you going to cook?

5. Mr. and Mrs.Smith are going shopping. (What/ they/ buy?)

-> What are they going to buy?

6. Ba is working hard for his exams. (When/ he/ have exams?)

-> When is he going to have exams ?

7. It's my birthday next week. (you/ have a birthday party?)

-> Are you going to have a birthday party?

8. Hoa's not going by bicycle. (she/ go/ bus?)

-> Is she going by bus?

9. We aren't going to have a meeting on Friday. (you/ have a meeting/ Saturday?)

-> Are you going to have a meeting on Saturday?

Ta có: \(\frac{4}{x+2}+\frac{2}{x-2}+\frac{5x-6}{4-x^2}=\frac{4x-8+2x+4+5x-6}{4-x^2}=\frac{11x-2}{4-x^2}\)

Đổi :40 phút = \(\frac{2}{3}\)giờ 

Vận tốc của con ngựa :30 :\(\frac{2}{3}\)=45km/giờ