Gọi x (quyển), y (quyển), z (quyển) lần lượt là số sách Toán, Tiếng Anh, Văn học (x, y, z )

Theo đề bài, ta có:

x/3 = y/2 ⇒ x/21 = y/14 (1)

y/7 = z/9 ⇒ y/14 = z/18 (2)

Từ (1) và (2) ⇒ x/21 = y/14 = z/18

Áp dụng tính chất của dãy tỉ số bằng nhau, ta có:

x/21 = y/14 = z/18 = (x + y + z)/(21 + 14 + 18) = 318/53 = 6

x/21 = 6 ⇒ x = 6.21 = 126 (nhận)

Vậy số sách Toán là 126 quyển

hihi^^

???

Đề TA

I. Điền hình thức đúng của động từ trong ngoặc:

1/ The Sun (rise) in the east and (set) in the west.

2/ My grandma (use) to tell me the folktales.

3/ She (not ) playing soccer.

4/ Where you (be) going to visit next summer?

I (visit) Hue.

5/ They (work) in this company for ten years.

6/ My mother has to (clean)the floor everyday.

7/ He (not write)to his friend since Monday.

8/ Students must (go) to school on time.

9/ I (get) a letter from my old friend yesterday

10/ Where he (use to)live before he moved here?

II. Hoàn thành các câu sau, dùng hình thức so sánh phù hợp:

1/ My house isn't as (big) her house.

2/ Milk is (expensive) than mineral water.

3/ This hotel is (cheap) in the town.

4/ She is wearing a hat (same) mine

5/ Ho Chi Minh City is (big) than Ha Noi.

6/ February is (short) of the year.

7/Life in the city is (busy).

8/ Nam is (intelligent) in my class.

9/ Lan is (pretty) as her sister.

10/ Her hobbies are (different) from yours

IV. Điền vào mỗi chỗ trống với một giới từ đúng

1/ They have built this house..............a long time.

2/ We have lived .....An Lao.....14 years.

3/ There are some books........the table........the right corner.......the room

4/ The course begins......January and ends .....April.

5/ I usually watch TV ......the evening.

6/ The stadium is in............of my house.

7/ He often gets up..........5.30...........the morning but.......Sunday morning he gets up late.

8/ English learners learn words ..............different ways

9/ Thank you very much ...........lending me your bike

10/ I got good grades.............English and Math last semester

11/ All students enjoy taking part ............outdoor activities

12. Should should learn ............heart these new words.

V. Hoàn thành các câu sau dùng đại từ phản thân phù hợp

1/ My brother can repair the bike ....................

2/ They have a great time. They really enjoy ......................

3/ Don't worry about us. We can look after ...................

4/ This exercise isn't difficult. Do it ...................

5/ She cut ....................

6/ I made this shirt ....................

VI. Đặt câu hỏi cho từ gạch chân:

1/ Hoa went to school late this morning because her bike broke down

2/ I have to tidy the living room everyday

3/ She'll be home after dinner

4/ Lan used to live on the farm when she was young

5/ My mother gave me a new bike on my 14th birthday

6/ Nam often walks to school

7/ I need to improve Math and English

8/ Nga studied well this semester

9/ We have studied English for 4 years

10/ My best friend is very helpful and friendly

VII. Viết lại các câu sau sao cho nghĩa không đổi

1. "Can you carry these chairs into the house?"

Mrs Lan asked me ...........................................................................

2. "Please give me your book?"

He told me .......................................................................................

3. You shouldn't make noise in class."

The teacher said .............................................................................

4. "Can you help Tam with his English pronunciation?"

Mr Hung asked me ..........................................................................

5. My hobbies are playing sports and reading books

I love ................................................................................................

6. She was born on May 10th, 1996

Her birthday .....................................................................................

7. Nga must wash the dishes everyday

Nga has ...........................................................................................

8. We began to study English 4 years ago

We have ..........................................................................................

9. No one in class is as tall as Tam

Tam is the ........................................................................................

10. Women often did the house work without the help of modern equipment in the past In the past women used

VIII. Dùng từ gợi ý viết thành câu hoàn chỉnh

1. Thanh/ tall/ thin/ long/ straight/ hair

.........................................................................................................

2. His father/ generous/ friendly

.........................................................................................................

3. They/ going to/ have a meeting/ the weekend

.........................................................................................................

4. We/ must/not/ let/ children/ the kitchen/ because/ it/ dangerous place

.........................................................................................................

5. The Y&Y members/ going to/ take part/ recycling program/ save natural resources /and/ money/ the organization

.........................................................................................................

6. I/ a favor/ you help/ carry this bag?

.........................................................................................................

7. The town/ becoming/ beautiful

.........................................................................................................

8. My father/ used/ drive a car/ work/ now/ go/ bus

.........................................................................................................

9. I/ spend/ 2 hours/ day/ study English

.........................................................................................................

10. Alexander Graham Bell/ born/ Edinburgh/ March 3, 1847

......................................................................................................... 

I. Điền hình thức đúng của động từ trong ngoặc:

1/ The Sun (rise) in the east and (set) in the west.

2/ My grandma (use) to tell me the folktales.

3/ She (not ) playing soccer.

4/ Where you (be) going to visit next summer?

I (visit) Hue.

5/ They (work) in this company for ten years.

6/ My mother has to (clean)the floor everyday.

7/ He (not write)to his friend since Monday.

8/ Students must (go) to school on time.

9/ I (get) a letter from my old friend yesterday

10/ Where he (use to)live before he moved here?

II. Hoàn thành các câu sau, dùng hình thức so sánh phù hợp:

1/ My house isn't as (big) her house.

2/ Milk is (expensive) than mineral water.

3/ This hotel is (cheap) in the town.

4/ She is wearing a hat (same) mine

5/ Ho Chi Minh City is (big) than Ha Noi.

6/ February is (short) of the year.

7/Life in the city is (busy).

8/ Nam is (intelligent) in my class.

9/ Lan is (pretty) as her sister.

10/ Her hobbies are (different) from yours

IV. Điền vào mỗi chỗ trống với một giới từ đúng

1/ They have built this house..............a long time.

2/ We have lived .....An Lao.....14 years.

3/ There are some books........the table........the right corner.......the room

4/ The course begins......January and ends .....April.

5/ I usually watch TV ......the evening.

6/ The stadium is in............of my house.

7/ He often gets up..........5.30...........the morning but.......Sunday morning he gets up late.

8/ English learners learn words ..............different ways

9/ Thank you very much ...........lending me your bike

10/ I got good grades.............English and Math last semester

11/ All students enjoy taking part ............outdoor activities

12. Should should learn ............heart these new words.

V. Hoàn thành các câu sau dùng đại từ phản thân phù hợp

1/ My brother can repair the bike ....................

2/ They have a great time. They really enjoy ......................

3/ Don't worry about us. We can look after ...................

4/ This exercise isn't difficult. Do it ...................

5/ She cut ....................

6/ I made this shirt ....................

VI. Đặt câu hỏi cho từ gạch chân:

1/ Hoa went to school late this morning because her bike broke down

2/ I have to tidy the living room everyday

3/ She'll be home after dinner

4/ Lan used to live on the farm when she was young

5/ My mother gave me a new bike on my 14th birthday

6/ Nam often walks to school

7/ I need to improve Math and English

8/ Nga studied well this semester

9/ We have studied English for 4 years

10/ My best friend is very helpful and friendly

VII. Viết lại các câu sau sao cho nghĩa không đổi

1. "Can you carry these chairs into the house?"

Mrs Lan asked me ...........................................................................

2. "Please give me your book?"

He told me .......................................................................................

3. You shouldn't make noise in class."

The teacher said .............................................................................

4. "Can you help Tam with his English pronunciation?"

Mr Hung asked me ..........................................................................

5. My hobbies are playing sports and reading books

I love ................................................................................................

6. She was born on May 10th, 1996

Her birthday .....................................................................................

7. Nga must wash the dishes everyday

Nga has ...........................................................................................

8. We began to study English 4 years ago

We have ..........................................................................................

9. No one in class is as tall as Tam

Tam is the ........................................................................................

10. Women often did the house work without the help of modern equipment in the past In the past women used

VIII. Dùng từ gợi ý viết thành câu hoàn chỉnh

1. Thanh/ tall/ thin/ long/ straight/ hair

.........................................................................................................

2. His father/ generous/ friendly

.........................................................................................................

3. They/ going to/ have a meeting/ the weekend

.........................................................................................................

4. We/ must/not/ let/ children/ the kitchen/ because/ it/ dangerous place

.........................................................................................................

5. The Y&Y members/ going to/ take part/ recycling program/ save natural resources /and/ money/ the organization

.........................................................................................................

6. I/ a favor/ you help/ carry this bag?

.........................................................................................................

7. The town/ becoming/ beautiful

.........................................................................................................

Gọi điểm môn Toán bạn An cần làm là x(điểm)

(Điều kiện: x>0)

Trung bình điểm kiểm tra của An là: \(\dfrac{8\cdot2+7+9+x\cdot2}{2+1+2+1}=\dfrac{2x+32}{6}\)

Để đạt từ 8,0 trở lên thì \(\dfrac{2x+32}{6}>=8\)

=>2x+32>=48

=>2x>=16

=>x>=8

vậy: An cần ít nhất 8 điểm môn Toán để được xếp loại giỏi

Gọi số điểm Toàn bạn An phải làm được ít nhất để được HSG là x(x>=6,5)

Theo đề, ta có: \(\dfrac{8\cdot2+x\cdot2+7+9}{2+2+1+1}>=8.0\)

=>16+2x+16>=8*6=48

=>2x+32>=48

=>2x>=16

=>x>=8

=>Cần phải làm được ít nhất là 8 điểm bài Toán mới được HSG

Gọi x là điểm thi môn Toán (x ≤ 10).

Vì môn Văn và Toán được tính hệ số 2 nên ta có điểm trung bình của Chiến là:

Theo đề bài, để đạt loại Giỏi thì điểm môn Toán của Chiến phải thỏa mãn điều kiện: x ≥ 6 (1) và  (2).

Xét (2):  ⇔ 2x + 33 ≥ 48 ⇔ 2x ≥ 15 ⇔ x ≥ 7,5.

Kết hợp với (1) ta được: x ≥ 7,5.

Vậy để đạt được loại giỏi thì bạn Chiến phải có điểm thi môn Toán thấp nhất là 7,5 điểm.

\(=\frac{\left(x^3\right)^2-\left(y^3\right)^2}{\left[\left(x^2\right)^2-\left(y^2\right)^2\right]-xy\left(x^2-y^2\right)}=\)

\(=\frac{\left(x^3-y^3\right)\left(x^3+y^3\right)}{\left(x^2-y^2\right)\left(x^2+y^2\right)-xy\left(x^2-y^2\right)}=\)

\(=\frac{\left(x+y\right)\left(x^2-xy+y^2\right)\left(x-y\right)\left(x^2+xy+y^2\right)}{\left(x^2-y^2\right)\left(x^2+y^2-xy\right)}=\)

\(=\frac{\left(x^2-y^2\right)\left(x^2-xy+y^2\right)\left(x^2+xy+y^2\right)}{\left(x^2-y^2\right)\left(x^2-xy+y^2\right)}=x^2+xy+y^2\)

Cảm ơn bạn Nguyễn Ngọc Anh Minh nhiều nha! :)

Gọi x là điểm thi môn Toán, theo đề bài ta có điều kiện: 6 ≤ x ≤ 10

Vậy để đạt được loại giỏi thì bạn Chiến phải có điểm thi môn Toán thấp nhất là 7,5 điểm