Có bao nhiêu số nguyên âm m để phương trình  m = l o g 3 3 x + 1 3 x + 3 - 27 có nghiệm thực

A. 3.

B. 2.

C. 4.

D. 5.

Cho biết M ( x )   +   ( x 3   +   5 x 2   -   7 x   +   1 )   =   3 x 4   +   x 3   -   7 . Câu nào sau đây đúng:

A.  M ( x )   =   3 x 4   +   x 3   -   7

B. Bậc của M(x) là 4

C. Hệ số cao nhất của M(x) là 7

D. A, B đúng và C sai

Axit H 3 PO 4   và   HNO 3  cùng phản ứng được với tất cả các chất trong dãy

A.  MgO ,   BaSO 4 ,   NH 3 ,   Ca ( OH ) 2 .

B.  NaOH ,   KCl ,   NaHCO 3 ,   H 2 S .

C.  CuCl 2 ,   KOH ,   NH 3 ,   Na 2 CO 3 .

D.  KOH ,   NaHCO 3 ,   NH 3 ,   CaO .

Cho biết x và y là hai đại lượng tỉ lệ thuận theo hệ số k. Khi x = 12 thì y = -3. Hệ số tỉ lệ là:

A. k = -1/4

B. k = -4

C. k = 1/4

D. k = 4

Trong phản ứng hóa học giữa Ca và P, P đóng vai trò

A. vừa là chất oxi hóa vừa là chất khử.

B. không đó vai trò oxi hóa hay khử.

C. là chất oxi hóa.

D. là chất khử.

Chọn câu sai

A. ax – bx + ab –  x 2 =  x + b a - x

B. x 2  – y 2  + 4x + 4 =  x + y x - y + 4

C. ax + ay – 3x – 3y =  a - 3 x + y

D. xy + 1 – x – y =  x - 1 y - 1

Read the passage carefully and choose the correct answer.

Family conflict

The generation gap, which refers to a broad difference between one generation and another, especially  between young people and their parents, usually leads to numerous conflicts. Such family conflicts can seriously threaten the relationship between parents and children at times. It goes without saying that, however old their children are, parents still regard them as small kids and keep in mind that their offspring are too young to protect themselves cautiously or have wise choices. Therefore, they tend to make a great attempt to help their children to discover the outside world. Nevertheless, they forget that as children grow up, they want to be more independent and develop their own identity by creating their own opinions, thoughts, styles and values about life. One common issue that drives conflicts is the clothes of teenagers. While teens are keen on wearing fashionable clothes which try to catch up with the youth trends, parents who value traditional clothes believe that those kinds of attire violate the rules and the norms of the society. It becomes worse when the expensive brand name clothes teens choose seem to be beyond the financial capacity of parents. Another reason contributing to conflicts is the interest in choosing a career path or education between parents and teenagers. Young people are told that they have the world at their feet and that dazzling future opportunities are just waiting for them to seize. However, their parents try to impose their choices of university or career on them regardless of their children's preference. Indeed, conflicts between parents and children are the ever lasting family phenomena. It seems that the best way to solve the matter is open communication to create mutual trust and understanding.

Which can be the best title for the passage?

A. Where do parent-child conflicts come from?

B. How are children different from their parents?

C. How do we bridge the generation gap?

D. X