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Cho một hình vuông có cạnh là 1dm. Chúng tôi đang vẽ những trung tâm lần lượt là A, B, C, D. Các bán kính của bốn ô vuông là 1dm, quá. Bốn vuông có một phần chung. Đó là MNPQ. Tìm diện tích của MNPQ.
LƯU Ý
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Chuyên mục Giúp tôi giải toán dành cho những bạn gặp bài toán khó hoặc có bài toán hay muốn chia sẻ. Bởi vậy các bạn học sinh chú ý không nên gửi bài linh tinh, không được có các hành vi nhằm gian lận điểm hỏi đáp như tạo câu hỏi và tự trả lời rồi chọn đúng.
is .............
câu 9.Let ABCD be a trapezoid with bases AB, CD and O be the intersection of AC and BD. If the areas of triangle OAB, triangle OCD are 16cm2, 40cm2respectively and M is the midpoint of BD, then the area of the triangle AMD is .........cm2.
câu 10.Bottle A contains 15% syrup. Bottle B contains 40% syrup. When these 2 bottles of syrup are mixed, the syrup content is 30% and the total volume is 600ml. How much syrup is in the bottle A at first?
câu 11.Let ABCD.A'B'C'D' be a cube with AC' = √3cm. Find the total surface area of this cube.
câu 12.Let ABC be a triangle with AB = 3cm, AC = 7cm. The internal bisector of the angle BAC intersects BC at D. The line passing through D and parallel to AC cuts AB at E. Find the measure of DE.
câu 12.Given two numbers x, y such that (4y2 - 12y + 25)(4x2 + 6x + 4) = 28
câu 16.
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 55 to 64.
Overpopulation, the situation of having large numbers of people with too few resources and too little space, is closely associated with poverty. It can result from high population density, or from low amounts of resources, or from both. Excessively high population densities put stress on available resources. Only a certainnumber of people can be supported on a given area of land, and that number depends on how much food and other resources the land can provide. In countries where people live primarily by means of simple farming, gardening, herding, hunting, and gathering, even large areas of land can support only small numbers of people because these labor-intensive subsistence activities produce only small amounts of food.
In developed countries such as the United States, Japan, and the countries of Western Europe, overpopulation generally is not considered a major cause of poverty. These countries produce large quantities of food through mechanized farming, which depends on commercial fertilizers, large-scale irrigation, and agricultural machinery. This form of production provides enough food to support the high densities of people in metropolitan areas.
A country’s level of poverty can depend greatly on its mix of population density and agricultural productivity. Bangladesh, for example, has one of the world’s highest population densities, with 1,147 persons per sq km. A large majority of the people of Bangladesh engage in low-productivity manual farming, which contributes to the country’s extremely high level of poverty. Some of the smaller countries in Western Europe, such as the Netherlands and Belgium, have high population densities as well. These countries practice mechanized farming and are involved in high-tech industries, however, and therefore have high standards of living.
At the other end of the spectrum, many countries in sub-Saharan Africa have population densities of less than 30 persons per sq km. Many people in these countries practice manual subsistence farming; these countries also have infertileland, and lack the economic resources and technology to boost productivity. As a consequence, these nations are very poor. The United States has both relatively low population density and high agricultural productivity; it is one of the world’s wealthiest nations.
High birth rates contribute to overpopulation in many developing countries. Children are assets to many poor families because they provide labor, usually for farming. Cultural norms in traditionally rural societies commonly sanction the value of large families. Also, the governments of developing countries often provide
little or no support, financial or political, for family planning; even people who wish to keep their families small have difficulty doing so. For all these reasons, developing countries tend to have high rates of population growth.
From "Poverty" by Thomas J. Corbett
Which of the following is given a definition in paragraph 1?
- A. Poverty
- B. Population density
- C. Overpopulation
- D. Simple farming
-
Câu 2:
What will suffer when there are excessively high population densities?
- A. Available resources
- B. Farming methods
- C. Land area
- D. Skilled labor
-
Câu 3:
The phrase “that number” in paragraph 1 refers to the number of ______.
- A. resources
- B. countries
- C. people
- D. densities
-
Câu 4:
In certain countries, large areas of land can only yield small amounts of food because ______.
- A. there is an abundance of resources
- B. there is no shortage of skilled labor
- C. there are small numbers of laborers
- D. there is lack of mechanization
-
Câu 5:
Bangladesh is a country where the level of poverty depends greatly on ______.
- A. population density in metropolitan areas
- B. both population density and agricultural productivity
- C. its population density only
- D. its high agricultural productivity
-
Câu 6:
The phrase “engage in” in paragraph 3 is closest in meaning to ______.
- A. escape from
- B. look into
- C. give up
- D. participate in
-
Câu 7:
The word “ infertile ” in paragraph 4 probably means ______.
- A. impossible
- B. unproductive
- C. disused
- D. inaccessible
-
Câu 8:
Which of the following is TRUE, according to the passage?
- A. In sub-Saharan African countries, productivity is boosted by technology.
- B. There is no connection between a country’s culture and overpopulation.
- C. All small countries in Western Europe have high population densities.
- D. In certain developed countries, mechanized farming is applied.
-
Câu 9:
Which of the following is a contributor to overpopulation in many developing countries?
- A. High-tech facilities
- B. High birth rates
- C. Economic resources
- D. Sufficient financial support
-
Câu 10:
Which of the following could be the best title for the passage?
- A. High Birth Rate and its Consequences
- B. Poverty in Developing Countries
- C. Overpopulation: A Worldwide Problem
- D. Overpopulation: A Cause of Poverty
Dịch thôi chứ ko bt làm:Diện tích tam giác ABC là 300. Trong tam giác ABC, Q là trung điểm BC, P là một điểm trên AC nằm giữa C và A sao cho CP = 3PA. R là một điểm trên cạnh AB sao cho diện tích của \(\Delta\)PQR gấp đôi diện tích của \(\Delta\)RBQ. Tìm diện tích của\(\Delta\) PQR
Cho một hình chữ nhật mà chiều rộng của nó là một nửa chiều dài. Tỉ lệ giữa chu vi của hình chữ nhật với chiều rộng của nó là ?
Bài giải:
Gọi chiều rộng là: R; chiều dài là D; Chu vi là CV của hình chữ nhật
Theo đề bài ta có: R=1/2D. Suy ra D=2R
Mà chu vị hình chữ nhật là: CV = (D+R)x2.
Tỉ lệ giữa chu vi của hình chữ nhật với chiều rộng là: CV:R = (2R +R)x2 : R
= 3Rx2:R =6
Đáp án: 6
4. Call that polynomial P (x) = ax3 + bx2 + cx + d
We have P(1)=a+b+c+d=3 (1)
P(2)=8a+4b+2c+d=3 (2)
P(3)=27a+9b+3c+d =7 (3)
P(4)=64a+16b+4c+d =21 (4)
From (1) and (2) => 7a+3b+c=0
From (1) and (4) => 63a+15b+3c=18
=> 12b+6c=-18 => 2b+c=-3
From (1) and (3) =>26a+8b+2c=4=> 13a+4b+c=2
=> 13a+2b=5
It is possible