A=1.21​+3.41​+5.61​+...+49.501​

\(\mathit{A} = \left(\right. 1 + \frac{1}{3} + \frac{1}{5} + . . . + \frac{1}{49} \left.\right) - \left(\right. \frac{1}{2} + \frac{1}{4} + . . . + \frac{1}{50} \left.\right)\)

\(\mathit{A} = \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + . . . + \frac{1}{49} + \frac{1}{50} \left.\right) - 2 \left(\right. \frac{1}{2} + \frac{1}{4} + . . . + \frac{1}{50} \left.\right)\)

\(\mathit{A} = \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + . . . + \frac{1}{49} + \frac{1}{50} \left.\right) - \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + . . . + \frac{1}{25} \left.\right)\)

\(\mathit{A} = \frac{1}{26} + \frac{1}{27} + . . . + \frac{1}{49} + \frac{1}{50} < \frac{1}{26} + \frac{1}{26} + \frac{1}{26} + . . . + \frac{1}{26} = \frac{25}{26} < 1.\)

Kim ngạch xuất khẩu của Việt Nam năm 2019 với thị trường châu Âu là:

\(135 , 45 - 88 , 18 = 47 , 27\) (tỉ USD)

Kim ngạch xuất khẩu của Việt Nam năm 2019 với thị trường châu Âu là:

\(47 , 27.156 , 32\) (tỉ USD)

Kim ngạch xuất khẩu của Việt Nam với thị trường châu Á lớn hơn tổng kim ngạch xuất khẩu của Việt Nam với thị trường châu Âu và châu Mỹ là:

\(135 , 45 - \left(\right. 47 , 27 + 73 , 89 \left.\right) = 14 , 29\) (tỉ USD).

A C B

Vì điểm \(\mathit{C}\) nằm giữa điểm \(\mathit{A}\) và điểm \(\mathit{B}\) nên:

\(\mathit{A} \mathit{C} + \mathit{C} \mathit{B} = \mathit{A} \mathit{B}\)

Thay \(\mathit{A} \mathit{C} = 2 , 5\) cm; \(\mathit{A} \mathit{B} = 5\) cm, ta có:

\(2 , 5 + \mathit{C} \mathit{B} = 5\)

\(\mathit{C} \mathit{B} = 5 - 2 , 5\)

\(\mathit{C} \mathit{B} = 2 , 5\) (cm).

b) Vì điểm \(\mathit{C}\) nằm giữa điểm \(\mathit{A}\) và điểm \(\mathit{B}\) và \(\mathit{A} \mathit{C} = \mathit{C} \mathit{B} = 2 , 5\) cm.

Nên điểm \(\mathit{C}\) là trung điểm của đoạn thẳng \(\mathit{A} \mathit{B}\). 

a) Môn Lịch sử và địa lí bạn Minh có ĐTB cao nhất trong học kì I.

b) Môn Toán bạn Minh có tiến bộ nhiều nhất.

c) ĐTB cả năm môn Toán là: \(\frac{7 , 9 + 2.8 , 6}{3} \approx 8 , 4\).

a) \(\frac{3}{4} + \frac{- 1}{3} + \frac{- 5}{18} = \frac{27}{36} + \frac{- 12}{36} + \frac{- 10}{36} = \frac{5}{36}\).

b) \(13 , 57.5 , 5 + 13 , 57.3 , 5 + 13 , 57 = 13 , 57. \left(\right. 5 , 5 + 3 , 5 + 1 \left.\right) = 13 , 57.10 = 135 , 7.\)

Renewable energy sources are important because they are clean, which means they don't harm the environment. They are also sustainable because they won't run out. Additionally, they help reduce pollution and greenhouse gas emissions. Using renewable energy can also create new job opportunities. Overall, renewable energy helps us protect the planet for future generations.

There are some students in the picture. There are many bookshelves around, so I guess they are studying in the library. The boy is carrying a laptop, while the girl is carrying many books. Two friends are discussing with each other. They might be reviewing and preparing for the upcoming exam.

1. My name is …

2. I ride my bicycle every day, usually in the morning or afternoon, for exercise and to get around town easily.

3. I like action and comedy films the most because they are exciting and make me laugh.

4. I joined the Lunar New Year festival because it's a traditional celebration with lots of food, performances, and fireworks.

5. I use electricity and sometimes gas for cooking at home because they are convenient and reliable sources of energy

1. The film was a success despite its low budget / having a low budget. 

2. You mustn’t throw trash out of your car window in traffic. 

3. The food at that stall was more delicious than the food at this one. 

4. There are not enough notebooks for the students. 

1.I think we will travel by hyperloop in the future. 

2.Traffic in big cities is often worse than in small towns.

3. Are there usually special activities for children at festivals?