Cho các số a,b,c thỏa mãn a+b+c=\(\dfrac{3}{2}\) chứng minh \(a^2+b^2+c^2\ge\dfrac{3}{4}\)

130 học sinh thuộc 3 lớp 7A; 7B, 7C của một trường cùng tham gia trồng cây. Mỗi học sinh của lớp 7A; 7B; 7C theo thứ tự trồng được 2 cây; 3 cây; 4 cây. Hỏi mỗi lớp có bao nhiêu học sinh tham gia trồng cây? Biết rằng số cây trồng được của ba lớp bằng nhau.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate thecorrect word or phrase that best fits each of the numbered blanks from 23 to 27.

In the early twentieth century, an American woman named Emily Post wrote a book on etiquette. This book explained the proper behavior Americans should follow in many different social (23)______, from birthday parties to funerals. But in modern society, it is not simply to know the proper rules for behavior in your own country. It is necessary for people (24)______ work or travel abroad to understand the rules of etiquette in other cultures as well. Cultural (25)______ can be found in such simple processes as giving or receiving a gift. In Western cultures, a gift can be given to the receiver with relatively little ceremony. When a gift is offered, the receiver usually takes the gift and expresses his or her thanks. (26)______, in some Asian countries, the act of gift-giving may appear confusing to Westerners. In Chinese culture, both the giver and receiver understand that the receiver will typically refuse to take the gift several times before he or she finally accepts it. In addition, to (27)______ respect for the receiver, it is common in several Asian cultures to use both hands when offering a gift to another person.
(Source: Reading Advantage by Casey Malarcher)

Điền vào ô 25.

A. differences

B. different 

C. differently 

D. differ

Tìm các số x; y; z biết:

a) x, y, z tỉ lệ với các số 4; 7; 3 và x + y + z = - 42

b) x, y, z tỉ lệ với các số 5; - 3; 8 và 3x -5y  -2z = 42

c)  x : y : z = 3 : 4 : 5 ; 2 x 2 + 2 y 2 − 3 z 2 = − 100

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate thecorrect word or phrase that best fits each of the numbered blanks from 23 to 27.

In the early twentieth century, an American woman named Emily Post wrote a book on etiquette. This book explained the proper behavior Americans should follow in many different social (23)______, from birthday parties to funerals. But in modern society, it is not simply to know the proper rules for behavior in your own country. It is necessary for people (24)______ work or travel abroad to understand the rules of etiquette in other cultures as well. Cultural (25)______ can be found in such simple processes as giving or receiving a gift. In Western cultures, a gift can be given to the receiver with relatively little ceremony. When a gift is offered, the receiver usually takes the gift and expresses his or her thanks. (26)______, in some Asian countries, the act of gift-giving may appear confusing to Westerners. In Chinese culture, both the giver and receiver understand that the receiver will typically refuse to take the gift several times before he or she finally accepts it. In addition, to (27)______ respect for the receiver, it is common in several Asian cultures to use both hands when offering a gift to another person.
(Source: Reading Advantage by Casey Malarcher)

Điền vào ô 24.

A. who

B. which 

C. where 

D. whose

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate thecorrect word or phrase that best fits each of the numbered blanks from 23 to 27.

In the early twentieth century, an American woman named Emily Post wrote a book on etiquette. This book explained the proper behavior Americans should follow in many different social (23)______, from birthday parties to funerals. But in modern society, it is not simply to know the proper rules for behavior in your own country. It is necessary for people (24)______ work or travel abroad to understand the rules of etiquette in other cultures as well. Cultural (25)______ can be found in such simple processes as giving or receiving a gift. In Western cultures, a gift can be given to the receiver with relatively little ceremony. When a gift is offered, the receiver usually takes the gift and expresses his or her thanks. (26)______, in some Asian countries, the act of gift-giving may appear confusing to Westerners. In Chinese culture, both the giver and receiver understand that the receiver will typically refuse to take the gift several times before he or she finally accepts it. In addition, to (27)______ respect for the receiver, it is common in several Asian cultures to use both hands when offering a gift to another person.
(Source: Reading Advantage by Casey Malarcher)

Điền vào ô 23.

A. positions

B. conditions 

C. situations 

D. locations

Tìm x,y biết:

a) 3 4 x + 1 5 = 1 6                      b)  1 3 + 1 2 : x = − 4                     c)  c ) x − 2 3 x + 1 4 = 0

d)  2 x − 3 3 4 x + 1 = 0           d) 2 3 x + 1 2 − 5 3 = 0                e)  2 x − 0 , 3 = 1 , 5

f)  x . − 3 5 3 = − 3 5 5           g)  x : 1 3 2 = 1 3 3                  h)  x 26 = 21 39

k)  1 3 x = 2 3 1 6                            l) 77 7 9 5 9 = x 0 , 03                       m) 2 2 3 0 , 03 = 1 7 9 x

n)  2 x − 3 2 = 16                      o) 3 x − 2 5 = − 243

Cho hàm số: f ( x ) = x 2 + 3 x + 2

a) Tính f(-1); f (0); f − 1 2

Số đôi của phân số - 3 8 là