Cho ba điểm A(4; 3), B(2; 7) và C(-3; -8).

a, Tìm tọa độ trọng tâm G và trực tâm H của tam giác ABC;

b, Gọi T là tâm đường tròn ngoại tiếp tam giác ABC. Chứng minh T, G và H thẳng hàng.

c, Viết phương trình đường tròn ngoại tiếp tam giác ABC.

Điều nào dưới đây là không đúng khi nói về CO

A. Là một oxit axit

B. Là chất khử mạnh

C. Chất khí không màu, không mùi, không vị, ít tan trong nước

D. Liên kết giữa C và O là liên kết ba

Hỏi cx chưa thấy ai trả lời

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.

Do you ever wish you were more optimistic, someone who always (45)____ to be successful? Having someone around who always fears the worst isn't really a lot of (46)____ - we all know someone who sees a single cloud on a sunny day and says, 'It looks like rain.' But if you catch yourself thinking such things, it's important to do something about it.

You can change your view of life, according to psychologist. It only takes a little (47)___, and you'll find life more rewarding as a (48)____. Optimism, they say, is partly about self-respect and confidence but it's also a more positive way of looking at life and all it has to (49)____. Optimists are more (50)_____ to start new projects and are generally more prepared to take risks.

Upbringing is obviously very important in forming your (51)___ to the world. Some people are brought up to depend too much on others and grow up forever blaming other people when anything (52)____ wrong. Most optimists, on the (53)____ hand, have been brought up not to (54)____ failure as the end of the world - they just get on with their lives.

Điền vào ô 49

A. supply 

B. suggest

C. offer

D. propose

Reading 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

After two decades of growing student enrollments and economic prosperity, business schools in the United States have started to face harder times. Only Harvard's MBA School has shown a substantial increase in enrollment in recent years. Both Princeton and Stanford have seen decreases in their enrollments. Since 1990, the number of people receiving Masters in Business Administration (MBA) degrees, has dropped about 3 percent to 75,000, and the trend of lower enrollment rates is expected to continue

There are two factors causing this decrease in students seeking an MBA degree. The first one is that many graduates of four-year colleges are finding that an MBA degree does not guarantee a plush job on Wall Street, or in other financial districts of major American cities. Many of the entry-level management jobs are going to students graduating with Master of Arts degrees in English and the humanities as well as those holding MBA degrees. Students have asked the question, "Is an MBA degree really what I need to be best prepared for getting a good job?" The second major factor has been the cutting of American payrolls and the lower number of entry-level jobs being offered. Business needs are changing, and MBA schools are struggling to meet the new demands

Which of the following business schools has NOT shown a decrease in enrollment?

A. Princeton                   

B. Harvard           

C. Stanford          

D. Yale

Nung m gam hỗn hợp gồm Mg và Cu(NO₃)₂ trong điều kiện không có không khí, sau một thời gian thu được chất rắn X và 10,08 lít (đktc) hỗn hợp khí gồm NO₂ và O₂. Hòa tan hoàn toàn X bằng 650 ml dung dịch HCl 2M, thu được dung dịch Y chỉ chứa 71,87 gam muối clorua và 0,05 mol hỗn hợp khí Z gồm N₂ và H₂. Tỉ khối của Z so với He bằng 5,7. Giá trị của m gần giá trị nào nhất sau đây?

A. 50.

B. 55.

C. 45.

D. 60.

Anilin có công thức là

A. C₆H₅OH

B. CH₃OH

C. CH₃COOH

D. C₆H₅NH₂