Trường hợp 1:\(\left(2x+1\right)^2\)= \(4x^2\)+4x+1

Trường hợp 2: (2x + 2).2=4x+4

Đáp án:         đề bị thiếu

Ex 1:Choose the correct option A, B, C or D to complete the sentences

1.Gathering and hunting still play an important role in the_______of the Laha.

A. economic B. economy C. economial D. economize

2._______ethnic group has a larger population, the Tay or the Ede?

A.What B. Why C. Which D. Who

3.Ethnic peoples in the mountains have a simple way of farming. They use basic tools to _______the farm work.

A. check B. work C. make D do

4.Many ethnic minority students have to ________a long way to their traditional way of life.

A. travel B. ride C. pass D.get

5.People_______some far-away mountainous regions still keep their traditional way of life.

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

Ex 2:Fill each blank with a word/phrase in the box.

items cultural special communal minority ethnic heritage festivals held local

1.The Gong Festival is__________annually in the Central Highlands.

2.If you go to Sa Pa, you can see many local people in colouful clothes sell their ___________products.

3.There many ________in our country when spring comes.

4.The cultural_________of the ethnic people in Viet Nam is very rich.

5.The ________ on display in the Museum of Ethnology is really interesting.

6.Which still plays an important role in the life of some_________people in the mountains?

7.In the Central Highlands, the biggest and tallest house in the village is the ________house.

8.The Hmong women have a________style of coulourful dress.

9.Although there are __________ exchanges between ethnic groups, they still the idebtity of colourful dress.

10. Most ethnic ___________peoples are good at farming work.

Help me!!!!! I was urgently needed!!!

Từ x1 đến x50 có 25 cặp

Suy ra tổng twg x1 đến x50 là: 25 x 1 = 25

Suy ra tổng tự x1 đén x51 phải là số đói của 25

Mà số đối của 25 là -25

Suy ra x51= -25

Vậy x51= -25