I am not intimidated by this question, but it can stimulate my interest. I think the apple tree is three times as big as the pear tree. If two kinds of trees are to be fertilized on the same day, Master Lao Wang will fertilize "20×3" apple trees and 20 pear trees every day. In fact, he only fertilizes 50 apple trees every day, which is 10, and the last 80 trees. Therefore, Master Lao Wang has been fertilizing for 8 days. 20 pear trees a day, 8 days is 160 pear trees. According to the first condition, there are 480 apple trees. This is to solve the problem with the idea of hypothesis, so I think the hypothesis method is really a good way to solve the problem.
I met another math problem today, and it took me a lot of effort to solve it. The topic is: there are 30 birds in two trees, and 4 birds fly away from the second tree first. At this time, tree A flew to tree B with three birds, and the birds on the two trees were just equal. How many birds are there in each tree?
As soon as I saw the topic, I knew it was a reduction problem, so I solved it by the method of reduction problem. But when I checked, I found something was wrong. I will do it again more seriously. I think there are as many as four missing, half of them are 13, and the restored B-tree is14; A tree is 16. The formula is: (30-4) ÷ 2 = 13 (only); 13-3+4 =14 (only); 30- 14 = 16 (only). The answers are: a tree 16 and b tree 14.
By solving this problem, I understand that no matter what I do, I should be careful, otherwise, even if I master the solution to the problem, the result will be wrong.
Defendant: Sour Fish-Chief Operating Officer1Level 3 June 3, 2009 at 20: 29.
It rained on the night of Monday, April 7, 2003.
I used to think that learning the knowledge of "finding the least common multiple" was boring, and it was really annoying to deal with the problem of "finding the least common multiple of 1 1 2" all day. I have always felt that it is useless to learn this knowledge in my life. However, one thing changed my view. That was not long ago. Grandpa and I went to the Youth Palace by bus. My father and I took the No.3 bus and were about to leave when the 1 bus just took us away. At this moment, grandpa looked at two cars and suddenly smiled and said to me, "Xiao Ying, grandpa has a question to test you, okay?" "I answered with confidence," OK! " "That you listen up, if the 1 bus runs every 3 minutes, then the No.3 bus runs every 5 minutes. How many minutes will it take for these two cars to start at the same time? " After a pause, I said, "Grandpa, you can't solve this problem. "Grandpa looked at me doubtfully." Really? There is still one condition missing in this problem: 1 bus and bus No.3 start at the same place. Grandpa listened to my words, suddenly patted his clever bald head and said with a smile, "I am a doctor of mathematics, and sometimes I get confused. My questions are not rigorous enough, but I will still think carefully." Grandpa and I laughed happily. Then grandpa said, "OK, now suppose it's the same starting point. How do you solve it? " "I thought about it and blurted out," 15 minutes. Because 3 and 5 are prime numbers, finding the least common multiple of prime numbers is equal to the product of these two numbers (3х5= 15), so 15 is their least common multiple. In other words, two cars can leave at the same time in at least 15 minutes. Grandpa praised me: "The answer is correct! 100 points. " "Yes!" After listening to grandpa's words, I raised my hand happily. From this incident, I understand a truth: mathematical knowledge is really everywhere in real life.
Have you ever heard of the problem of "chickens and rabbits in the same cage" This question is one of the famous and interesting questions in ancient China. About 1500 years ago, this interesting question was recorded in Sun Tzu's calculation. The book describes it like this: "There are chickens and rabbits in the same cage today, with 35 heads on the top and 94 feet on the bottom. The geometry of chicken and rabbit? These four sentences mean: there are several chickens and rabbits in a cage, counting from the top, there are 35 heads; It's 94 feet from the bottom. How many chickens and rabbits are there in each cage?
Can you answer this question? Do you want to know how to answer this question in Sunzi Suanjing?
The answer is this: If you cut off the feet of every chicken and rabbit in half, then every chicken will become a "one-horned chicken" and every rabbit will become a "two-legged rabbit". In this way, the total number of feet of (1) chickens and rabbits changed from 94 to 47. (2) If there is a rabbit in the cage, the total number of feet is more than the total number of heads 1. So the difference between the total number of feet 47 and the total number of heads 35 is the number of rabbits, that is, 47-35 = 12 (only). Obviously, the number of chickens is 35- 12 = 23.
This idea is novel and strange, and its "foot-cutting method" has also amazed mathematicians at home and abroad. This way of thinking is called reduction. Reduction method means that when solving a problem, we do not directly analyze the problem first, but deform and transform the conditions or problems in the problem until it is finally classified as a solved problem.
1 On August 23, 967, the Soviet Union1spacecraft suddenly had a vicious accident when it returned to the atmosphere-the parachute could not be opened. After studying it, the central leadership of the Soviet Union decided to broadcast the accident live to the whole country. When the announcer of the TV station announced in a heavy tone that the spacecraft would crash in two hours, the audience would witness astronaut Vladimir? After the news of komarov's martyrdom came out, the whole country was immediately shocked and people were immersed in great grief.
On TV, the audience saw the calm image of astronaut komarov. He smiled and said to his mother, "Mom, I can clearly see your image here, including every gray hair on your head. Can you see me clearly? " "Yes, you see very clearly. Son, everything is fine, don't worry! " At this time, komarov's daughter also appeared on the TV screen. She is only 12 years old. Komarov said, "Daughter, don't cry." "I don't cry ..." My daughter broke down in tears, but she fought back her grief and said, "Dad, you are a Soviet hero. I want to tell you that the hero's daughter will live like a hero! " Komarov told her daughter, "When you study, you should take every decimal point seriously. What happened today on Alliance 1 is because a decimal point was ignored during ground inspection ... "
Time is running out. There are only seven minutes before the spaceship crashes. Komalov waved to the national television audience and said, "Fellow citizens, please allow me to say goodbye to you in this vast space." String 3
Even a decimal point error will lead to a tragic farewell that can never be remedied.
Julius Caesar of ancient Rome famously said, "In war, great things are often the result of small things." In China's epigram, it's probably "a short trip makes a long regret".
Hello everyone! I am the happiest decimal point in the mathematics kingdom. Here, every number likes me very much, because I am naughty sometimes, so everyone calls me "smart card", "naughty boy", "naughty boy" and so on.
One day, I walked out of my house and went to the concert hall. Haha, I saw our general "100", so I got up secretly and jumped behind his "1". Hee hee, I changed "100" to "1". The musician 0.4 is playing on the stage. I ran up and jumped on the head of "0.4", and "0.4" suddenly became "0.4", a cyclic decimal. Hahaha! It really killed me. Just when I was making trouble, the security guard "0" caught me. Other numbers are far away, saying, "Hey, stay away from him, or you will be reduced to decimal by him." When I snickered, "0" said, "Don't be afraid, he can't stand me." In this way, I was forced by 0 to apologize to digital experts like100 and 0.4.
Do you think I am naughty after reading the above story? In fact, I am also kind. For example, when I went out that afternoon, I saw the number "50" bullying "6". I was very angry at that time. I immediately rushed over and jumped at the foot of "50" and scored him as "5". "5" saw that he was smaller than "6" and immediately ran away without a trace.
Look, this is me! A smart, happy, naughty and helpful decimal point.