Hai nguồn phát sóng kết hợp S₁, S₂ trên mặt nước cách nhau 10 cm dao động theo phương trình $u_1=u_2=2\cos \left(40\pi t\right)$ cm. Xét điểm M trên mặt nước cách S₁, S₂ những đoạn tương ứng là d₁ = 4,2 cm và d₂ = 9 cm. Coi biên độ sóng không đổi và tốc độ truyền sóng trên mặt nước là v = 32 cm/s. Giữ nguyên tần số f và các vị trí S₁, M. Muốn điểm M nằm trên đường cực tiểu giao thoa thì phải dịch chuyển nguồn S₂ dọc theo phương S₁S₂ chiều lại gần S₁ từ vị trí ban đầu một khoảng nhỏ nhất bằng

Cho $\displaystyle \int f(x) \mathrm{d}x=x^2-3x+C.$ Khi đó $\displaystyle \int f\big(\mathrm{e}^{-x}\big) \mathrm{d}x$ bằng

Sau khi thực hiện các câu lệnh sau, mảng A như thế nào?

>>> A = [1, 2, 3, 4, 5]

>>> A. remove(2)

>>> print(A)

Read the following passage about education in Nepal and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questions from 31 to 40. 

A few years ago, amid a record drought, scientists noticed something odd. A few of California’s giant sequoias inside Sequoia and Kings Canyon National Parks were dying in ways no one had ever documented – from the top down. When researchers climbed into the canopies, they discovered that beetles had bored into a few branches. By 2019, at least 38 of the trees had died – not a large number, but "concerning because we’ve never observed this before,” says Christy Brigham, the park’s chief of resource management.

Scientists had assumed that stately sequoias, with their bug-repelling tannins, were immune to dangerous pests. Worried experts are investigating whether some mix of increased drought and wildfire, both worsened by climate change, have now made even sequoias susceptible to deadly insect invasions.

If so, these ancient sentinels would be just the latest example of a trend experts are documenting around the world: Trees in forests are dying at increasingly high rates—especially the bigger, older trees. According to a study in the journal Science, the death rate is making forests younger, threatening biodiversity, eliminating important plant and animal habitat, and reducing forests’ ability to store excess carbon dioxide generated by our consumption of fossil fuels. [A]

There is no single direct cause. Decades of logging and land clearing play a role, scientists say. But increasing temperatures and rising carbon dioxide from the burning of fossil fuels have significantly magnified most other causes of tree death. Scientists are documenting longer and harsher droughts, more severe outbreaks of insects and disease, and increasingly catastrophic wildfires.

With 60,000 known tree species on Earth, those shifts are playing out differently across the planet. In central Europe, for instance, “You don’t have to look for dead trees,” says Henrik Hartmann, with Germany's Max Planck Institute for Biogeochemistry. “They’re everywhere.” In one recent year, following a week of excessive heat, hundreds of thousands of beech trees dropped their leaves. Even in colder regions, “You get a couple of hot years and the forests are suffering,” says Hartmann. “There are individual species that are being driven beyond the threshold of what they can handle.” [B]

Just last year, massive fires marched through a dry Australia, smoldered across 7.4 million acres in northern Siberia, and focused the world’s attention on blazes in the Amazon.

The consequences of all these changes around the world are still being assessed. The first national look at tree mortality in Israel showed vast stretches disappearing, thanks largely to scorching heat and wildfires. [C] In a country largely blanketed by stone and sand, forests mean a great deal. Trees support nests for eagles and habitat for wolves and jackals. They hold soil with their roots. [D]

“We’re dealing with a very tough situation. It’s a race to the unknown,” says Tamir Klein at the Weizmann Institute of Science.

In which space (marked A, B, C and D in the passage) will the following sentence fit?

Without them, plants that normally rise in trees’ shadows are suddenly exposed to higher temperatures and bright light.

Theo em, giá bán thực tế của hàng hoá trên thị trường hay giá cả hàng hoá được thoả thuận giữa người mua và người bán được gọi là gì?

Tính đạo hàm của hàm số \(f(x)=x(x-1)(x-2) \cdots(x-2024)\) tại điểm \(x=0\) ?

Read the following leaflet and mark the letter A, B, C or D on your answer sheet to indicate the option that bestfits each of the numbered blanks from 7 to 12.

Tips for Better Time Management

Want to get more done in less time? Follow these strategies for improving your productivity and focus!

Common Struggles:

Many people ___(7)___ effective time management, leading to stress and unfinished tasks. Research shows that nearly 70% of workers feel overwhelmed by their workload.

Actionable Solutions!

● Prioritize your tasks! Start by making a to-do list and ___(8)___ the most important tasks first.

● Break down big projects! Tackling a large project can be daunting, but breaking it into smaller, manageable parts helps ___(9)___ progress without feeling overwhelmed.

● Avoid distractions! ___(10)___ multitasking, focus on one task at a time to ___(11)___ your efficiency.

● Take breaks! Give yourself regular breaks to rest and recharge, which can help maintain a higher ___(12)___ of productivity.

Nền kinh tế nước ta có bao nhiêu hoạt động kinh tế chủ yếu trong đời sống xã hội?

Những thành tựu khoa học, kĩ thuật của người Hy Lạp - La Mã cổ đại có ý nghĩa như thế nào?

Cơ chế thị trường có những ưu điểm nào sau đây?

Những việc làm nào dưới đây là vi phạm đạo đức sinh học?

Cho hai mệnh đề: $P$: "$30$ không chia hết cho $5$" và $Q$: "$\pi < 3,15$". Khẳng định nào sau đây đúng?

Nếu các số hữu tỉ $a, \, b$ thỏa mãn $\displaystyle \int\limits_0^1 (a\mathrm{e}^x + b) \mathrm{d}x = \mathrm{e} + 2$ thì giá trị của biểu thức $a+b$ bằng

Read the following advertisement and mark the letter A, B, C and D on your answer sheet to indicate the option that best fit each of the numbered blanks from 7 to 12

ASSISTANT MANAGER AT CAFÉ NEEDED

We are a busy café (7) ______in the West Village. This role is to help lead a great team at a popular spot in a lively neighborhood. Looking (8) ______someone with experience managing a coffee shop or cafe to help the owner keep the cafe running smoothly at a high standard and to maintain a (9) ______for our staff.

This is for someone ideally with coffee shop and Hospitality experience. The right (10) ______would be someone with out-of-the-box thinking who can help bring about improvements where needed and motivate and inspire (11) ______through great leadership.

These are the main responsibilities of the team you will lead. (12) ______, you would have to have good knowledge and skill with all.