At noon today, I did my math summer homework. Reading, reading, unfortunately encountered a thorny problem, I thought for a long time, I think this problem is like this:

There is a cuboid with two cells on the front and top, with an area of 209? The length, width and height of a square centimeter are prime numbers. Find its volume.

I saw him and thought: this question is really difficult! There are only two products with known area, and the volume also needs to know the length, width and height, which is not recommended. What should we do!

It's like I'm in a hurry, and one of my mom's colleagues is here. He taught me the idea of equation solution first, but my formula is not very familiar with this method. So, he taught me another way: first have a series, and then eliminate them one by one. At first, we asked to list a lot of numerical contents, such as: 3, 5, 7, 1 1 prime number, and then we began to solve. We found that there are only two numbers: 1 1 and 19. At this point, I think there is something wrong with these two phone numbers. One is in front of the rectangle, one is on top of the other.

Divide the side by the sum of the above foreign ministers (the length is prime). So, I began to distinguish between these two numbers, each number.

Finally, the result of 374 cubic centimeters was obtained. My formula is: 209 =119 = 2+171× 2×17 = 374 (cc).

Later, I learned to use the knowledge of this semester: check the exact same results of factorization problems.

I know I'm happier than anyone when something goes wrong. I also understand that mathematics is full of mysteries, waiting for us to explore the truth.

Math diary

August sixth

On Saturday night, I saw a math problem that would be confusing. Title: 37 students crossed the river, some took the ferry, and there were only 5 people on the empty boat. They should all cross the river. How many times have you wanted to use only one boat?

Careless people tend to ignore "empty boats" or forget gondolas, so you can only take four people. Subtract 37 students from gondola, leaving 36 students, and 36 divided by 4 equals 9. When the boatman went to the other side for the last time, four students went ashore, so he went there at least nine times.

The third in math diary.

August 9(th)

On Tuesday night, I read a book about the Olympic puzzle: orchard, apple tree and pear tree, three times a day, 50 Lao shifu Wang and 20 pear trees. A few days later, all the fertilizers were applied to the pears, and the remaining 80 apples were not fertilized. Let me ask you: How many apples and pears are there in the orchard?

I am not intimidated by this question, which can stimulate my interest. I think this is a pear tree that changed into two kinds of trees three times in the same day. If the finished product is fertilized, it should be the daily master of Lao Wang's "20×3" apple tree and pear tree. Although in fact he only fertilized 50 apples that day, poor 10 times, and finally 80 apples were rotten. From here, we can know that Master Lao Wang applied for 8 days of fertilization. 20 pear trees a day, pear eight days is 160, according to the first condition, we can know that the apple tree is 480. This is an idea? Hypothesis used to solve problems, so I think it is a good way to solve problems.

Math diary IV

August 4th 1 1

I met a math problem today and solved it easily. The topic is: two trees fly from 30 birds. The tree first flies to No.4 B, and then another tree flies to No.3 B. The bird trees of the two trees are exactly the same. How many birds are there in two trees?

I have a reading problem, you know, the problem of conversion, and then I will solve this problem by conversion. This error was discovered only after inspection. I will do it more carefully. I think, after as much as possible, half of 14 and 13 are reduced by B trees, and the trees are 16. The calculation formula is: (30-4)÷2 = 13 (only); 13-3 +4 = 14 (only); 30- 14 = 16 (only). The answer is: a, b tree 14 tree 16.

To solve this problem, I understand that no matter what kind of problem, we should be cautious, otherwise, even if we master the method to solve the problem, the result will be wrong.