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

đùa nhau à cái này làm sao pt dc

Gửi Thắng Nguyễn: Mình không biết tại sao lại ko phân tích được?

bằng cách nào bạn?? k đúng cho mình câu này nha.

bạn học lớp mấy vậy

\(\left\{{}\begin{matrix}x-y-z=0\\x+2y-10z=0\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}y=3z\\x=y+z=4z\\x+2y=10z\end{matrix}\right.\)

\(B=\dfrac{2x^2+4xy}{y^2+z^2}=\dfrac{2x\left(x+2y\right)}{9z^2+z^2}=\dfrac{2.4z.10z}{10.z^2}=8\)

TIẾNG ANH:

Đề kiểm tra 1 tiết môn Tiếng Anh lớp 8

A. PHONES: (1p)

1. A. children        B. chicken       C. chair         D. character

2. A. curly          B. shy          C. fly           D. sky 

3. A. joke          B. local         C. blond         D. sociable

4. A. fourteen       B. volunteer      C. seem         D. free

B. LANGUAGE FOCUS: (3ps)

I. Choose A, B, C, D for each gap in the following sentence. (2ps)

1. "Would you_________ to go to the movies with me?" – "I'd love to."

A.          B. want        C. love        D. mind

2. He is not ____________ get married.

A. enough old to     B. enough old for      C. old enough to         D. old enough for

3. Her mother ____________this city two years ago.

A. left          B. leaves        C. is leaving            D. will leave

4. Alexander Graham Bell was born __________ March 3, 1847.

A. in           B. on            C. at               D. during

5. Don't come in. Please wait _________ for your turn.

A. inside         B. downstairs      C. outside        D. upstairs

6. The children are old enough to look after __________.

A. themselves        B. ourselves        C. herself          D. for themselves

7. We ought __________ the wardrobe in the corner opposite the bed.

A. put               B. putting       C. to put               D. puts

8. The calendar is ________ the clock, _________ the picture and the lamp.

A. on/next to            B. under/between       C. behind/between       D. above/on

II. Supply the correct form of the verbs in the blanket. (1p)

1. We usually (go) ___________ to the library three times a week, but last week we (go) __________ twice.

2. Nga and Hoa (see) __________________ a movie tonight.

3. Sue can (speak) _______________ Vietnamese very well.

C. READING: (2ps)

I. Read the text and k in the true/ false column: (1p)

Do you have any close friends? I have two close friends, Hanh and Mai. We are in the same class. We are also neighbors. Hanh is a beautiful girl with big black eyes and an oval rosy face. She is an intelligent student who is always at the top of the class. She s reading, and she often goes to the library whenever she has free time. Mai isn't as beautiful as Hanh, but she has a lovely smile and looks very healthy. Mai is very sporty. She is a volleyball star of our school. She is very sociable and has a good sense of humor. I love both of my friends and I always hope our friendship will never die.

II. Read the text and answer the questions: (1p)

1. What does Hanh look ?

→ ...........................................................................................

2. Is she intelligent?

→ ...........................................................................................

3. What does Mai look ?

→ ...........................................................................................

4. Is she shy?

→ ...........................................................................................

D. WRITING: (4 ps)

I. Complete each sentence so it means the same as the sentence above. (2ps)

1. Peter is too young to see the horror film.

→ Peter is not old ...................................................................................

2. Hoa is older than Nien.

→ Nien is ...............................................................................................

3. The cat is on the gas stove.

→ The gas stove is ..................................................................................

4. Her hair is long and black.

→ She has ...............................................................................................

II. Put the words or phrase in correct order to make sentences. (2ps)

1. enough/ Jane/ strong/ the box./ to/ is/ lift

→ .................................................................................................................

2. you/ going to/ are/ What/ do/ next weekend?

→ .................................................................................................................

3. is/ Mai./ beautiful/ more/ Hanh/ than

→ .................................................................................................................

4. awful/ an/ What/ house!

→ ................................................................................................................

THE END -

ANSWER KEY:

A. PHONES: (1p)

1. A. children B. chicken C. chair D. character

2. A. curly B. shy C. fly D. sky

3. A. joke B. local C. blond D. sociable

4. A. fourteen B. volunteer C. seem D. free

B. LANGUAGE FOCUS: (3ps)

I. Choose A, B, C, D for each gap in the following sentence. (2ps)

1. “Would you_________ to go to the movies with me?” – “I’d love to.”

 B. want C. love D. mind

2. He is not ____________ get married.

enough old to B. enough old for C. old enough to D. old enough for

3. Her mother ____________this city two years ago.

left B. leaves C. is leaving D. will leave

4. Alexander Graham Bell was born __________ March 3, 1847.

in B. on C. at D. during

5. Don’t come in. Please wait _________ for your turn.

inside B. downstairs C. outside D. upstairs

6. The children are old enough to look after __________.

themselves B. ourselves C. herself D. for themselves

7. We ought __________ the wardrobe in the corner opposite the bed.

put B. putting C. to put D. puts

8. The calendar is ________ the clock, _________ the picture and the lamp.

on/next to B. under/between C. behind/between D. above/on

II. Supply the correct form of the verbs in the blanket. (1p)

1. We usually (go) ___ go ________ to the library three times a week, but last week we (go) __went________ twice.

2. Nga and Hoa (see) __will see / are going to see_____ a movie tonight.

3. Sue can (speak) ____ speak _____ Vietnamese very well.

C. READING: (2ps)

I. Read the text and k in the true/ false column: (1p)

Do you have any close friends? I have two close friends, Hanh and Mai. We are in the same class. We are also neighbors. Hanh is a beautiful girl with big black eyes and an oval rosy face. She is an intelligent student who is always at the top of the class. She s reading, and she often goes to the library whenever she has free time. Mai isn’t as beautiful as Hanh, but she has a lovely smile and looks very healthy. Mai is very sporty. She is a volleyball star of our school. She is very sociable and has a good sense of humor. I love both of my friends and I always hope our friendship will never die.

II. Read the text and answer the questions: (1p)

1. What does Hanh look ?

→ She is a beautiful girl with big black eyes and an oval rosy face.

2. Is she intelligent?

→ Yes, she is.

3. What does Mai look ?

→ She has a lovely smile and looks very healthy.

4. Is she shy?

→No, she isn’t.

D. WRITING: (4 ps)

I. Complete each sentence so it means the same as the sentence above. (2ps)

1. Peter is too young to see the horror film.

→ Peter is not old enough to see the horror film.

2. Hoa is older than Nien.

→ Nien is younger than Hoa.

3. The cat is on the gas stove.

→ The gas stove is under the cat.

4. Her hair is long and black.

→ She has long black hair.

II Put the words or phrase in correct order to make sentences. (2ps)

1. enough / Jane / strong / the box./ to / is / lift

→ Jane is strong enough to lift the box.

2. you / going to / are / What / do / next weekend?

→ What are you going to do next weekend?

3. is / Mai. / beautiful / more/ Hanh /...

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