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.
Math diary
It's the weekend again. Alas, the homework is finished, and it's another long day. How should I spend it? I was bored, so I took a copy of "100,000 Why" and held it up. "Alas, it is another book I have read." I complained.
"nonsense!" The door opened. Oh, it's dad. Right, I want to vent my anger! "Dad, I'm so bored!" "Boring is reading! Your father and I didn't have computers and televisions when we were young. " "But you won't go out to play for me ..." "By the way, I saw a math problem recently, and I was afraid ... Miss Liao Jia couldn't figure it out." Obviously, dad is keeping me in suspense. However, I, who have always been competitive, still can't stand this test and say, "Make a question!" "
"Let me tell a story first. There was a king in ancient India who loved to play. Once, I was ordered to post a list of talents throughout the country: whoever can find a wonderful game for the king will be rewarded. "
I got tired of waiting and said, "Come on!" Dad said, "Don't worry! Get down to business! A warlock published a list of talents. He invented a kind of chess that made the king reluctant to let go. The king asked the warlock happily, "What reward do you want? "The warlock said quickly," Your Majesty, I only ask you to put 1 grain of rice in the grid, put two grains of rice in the second grid, put four grains of rice in the third grid, and then put more rice in the back than the previous 1 lattice 1 times, and 64 grids will be full. " The king agreed. The question is, can the king give these rice prizes to the warlock?
Isn't it easy? I secretly brought my computer, and my dad said, "I dare you to use it." I'm a little flustered because my father doesn't joke.
Let's calculate that there are 1 grains of rice in 1 cell, 2 grains of rice in cell 2 and 4 grains of rice in cell 3 ... From 1 cell to cell 64, 2 must be multiplied 64 times, and then 1 is subtracted. After my one-hour calculation, the result is: 184677.
Why is this number so amazing? It turns out that this warlock skillfully takes 2 as the basic multiple, and the number of squares on the chessboard is 64 as the multiplicand of this multiple, so this 2 must be multiplied by 64 times. As for why 1 should be subtracted, it is because the first cell only has 1 grain of rice. 1 grain of rice, the number of 2 grains of rice is really small, but if this 2 is multiplied continuously, it will become a huge number. How can a king who lacks knowledge know?
Our society and life are full of math problems, and people with low math level are really easy to suffer. I have to hurry up and delve into the Olympic math problem.
Two, you choose one.