решение. 1. ri=2*r; rii=r/2; ri/rii=4; не надо ни о какой площади сечения говорить. два куска проволоки содинили последовательно, получили ri=2*r; два куска той же проволоки соединили параллельно, получили rii=r/2; ну, а теперь раздели первое на второе!
а теперь общий случай: ri=r*n; rii=r/n; ri/rii=n^2; кусок проволоки разрезали на n одинаковых кусков. сначала эти куски соединяют последовательно: ri=r*n; затем соединяют параллельно rii=r/n; ну и дели первое на второе и делай выводы.
If you go to school or university, you are faced with a number of exams. Basically, these exams are supposed to test your knowledge and skills. Also, they may motivate you to study harder.
In my opinion, it is really the case that exams motivate students to study harder. Firstly, exams are often a pass to a higher level of education. If you get good marks in examinations, you are admitted to further education. If you fail, you do not get the admittion. So, you make every effort to keep the right to study further. Secondly, exams are a good way to assess your learning efficiency and detect possible gaps in your knowledge. Bad marks mean that your knowledge is flawed and you need to be more disciplined and work harder to do away with the flaws.
But there are people who believe that examinations do not give real motivation to a student. They say that being a good student with excellent marks does not guarantee future prosperity.
Nevertheless, I cannot assent to the foregoing opinion, because being a good student is the beginning of being a good employee or worker who can earn a good living. Highly qualified professionals are always in great demand in any business sector.
In conclusion, exams play an important part in our life, although any exam is a kind of pain. But the saying is: no pain, no gain!
решение. 1. ri=2*r; rii=r/2; ri/rii=4; не надо ни о какой площади сечения говорить. два куска проволоки содинили последовательно, получили ri=2*r; два куска той же проволоки соединили параллельно, получили rii=r/2; ну, а теперь раздели первое на второе!
а теперь общий случай: ri=r*n; rii=r/n; ri/rii=n^2; кусок проволоки разрезали на n одинаковых кусков. сначала эти куски соединяют последовательно: ri=r*n; затем соединяют параллельно rii=r/n; ну и дели первое на второе и делай выводы.
If you go to school or university, you are faced with a number of exams. Basically, these exams are supposed to test your knowledge and skills. Also, they may motivate you to study harder.
In my opinion, it is really the case that exams motivate students to study harder. Firstly, exams are often a pass to a higher level of education. If you get good marks in examinations, you are admitted to further education. If you fail, you do not get the admittion. So, you make every effort to keep the right to study further. Secondly, exams are a good way to assess your learning efficiency and detect possible gaps in your knowledge. Bad marks mean that your knowledge is flawed and you need to be more disciplined and work harder to do away with the flaws.
But there are people who believe that examinations do not give real motivation to a student. They say that being a good student with excellent marks does not guarantee future prosperity.
Nevertheless, I cannot assent to the foregoing opinion, because being a good student is the beginning of being a good employee or worker who can earn a good living. Highly qualified professionals are always in great demand in any business sector.
In conclusion, exams play an important part in our life, although any exam is a kind of pain. But the saying is: no pain, no gain!