How to plant ten trees, plant five elements, and plant four trees in each row?

Plant according to the five sides of the pentagram.

This is a question in the Primary School Mathematics Olympiad, under normal circumstances, planting five elements, four trees in each row requires twenty trees, but only ten trees are given in the question, and here you need to change your thinking to solve.

The tree is required to be in rows, that is, it needs to be in a straight line; Each tree must be shared repeatedly, and it is obvious that the straight lines formed by the tree must have an intersection point in order to be shared. If there are already 10 trees and there are 10 trees missing, then all the 10 trees must be shared, which means that each tree must belong to at least two straight lines, that is, the straight lines formed by the trees must intersect in pairs. According to this analysis, we try to do this, and the five straight lines should intersect in pairs.

The resulting pattern can be what we often call a pentagram.

can also not be in the shape of a pentagram. As long as 5 straight lines intersect in pairs, and each straight line has 4 intersection points, that is, 4 trees, and the intersection points are not repeated, and each tree participates in the sharing.

This is a simple permutation problem that can be solved using the following steps:

There are five rows with four trees planted in each row, so the total number of trees that need to be planted is $5 times 4=20$ trees.

There are now $10$ trees, which is not enough to meet this demand.

It was not possible to plant trees as required, so the requirement of four trees per row could not be achieved.

Draw a five-pointed star and plant trees at the vertices and intersections.

Ten trees are planted in five rows, and four trees in each row are planted as follows:

1. As shown in the figure below, there are 10 trees, and 5 rows of trees need to be planted, 4 in each row, so each tree needs to be shared.

2. It can be achieved with the help of the shape of the pentagram, because the 10 endpoints of the pentagram are shared in pairs.

3. First place 5 trees at the inner endpoint of the pentagram, so that 5 rows of 2 trees are realized;

4. Place another five trees on the outer end of the pentagram, as shown in the figure below;

5. Using this principle, each of the 10 trees is shared in pairs, and the effect is magnified twice, and the placement effect is realized. Filial piety.

Induction of simple methods for elementary school mathematics.

1. Extract the common factor: This method actually uses the multiplicative distributive law to extract the same factor, and the remaining terms in the exam are often added and subtracted, and an integer will appear. (Note the extraction of the same factor).

2. Borrowing and borrowing method: When you see the name, you know the meaning of this method. When using this method, you need to pay attention to the macro and find the pattern.

Also pay attention to repay, there is borrowing and repaying, and it is not difficult to borrow again. In exams, when you see something like or close to a very good integer, you often use the borrowing-borrowing method.

3. Splitting Qiaotan method: The splitting method is to facilitate the calculation of splitting a number into several numbers. This requires mastering some "good friends" such as: 2 and 5, 4 and 5, 2 and, 4 and, 8 and so on.

Summary. The answer is to plant in the shape of a five-pointed star.

There are ten trees to be planted, and it is required to be planted in five elements, and four trees must be planted in each row.

The answer is to plant in the shape of a five-pointed star.

The answer is to plant in the shape of a five-pointed star.

The shape is shown in the image above.

These trees are planted in the arrangement of the regular five-pointed stars, and the green dots are ten trees.

1. The five lines of the five stars are five rows of spring grips, and the four intersections of each row of pickpocketing lines are four trees.

2. Each row has an overlap (that is, one less tree can be planted), a total of five rows, saving ten.

3. If it is arranged in a rectangle, 20 trees are needed. Therefore, the arrangement of the pentagram is only: 20-10=10 (trees).

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Mathematics application problem solving skills

1. When we encounter a big math problem, we should first read the problem carefully to find out the known and unknown conditions in the problem, and we can set the unknown conditions as x, y ??According to the proposition, the equation (group) and other Pixin formulas should be listed, and at least a few equations should be listed if there are a few unknowns.

The general idea is to let the unknown conditions establish an equation (group) equation relationship with the known conditions, and then use the known conditions in the problem.

2. Divide into parts.

If you encounter a very complex mathematical problem, you can first break it down into a number of small problems that are not too complicated, and then use the first step to solve each small problem: who sets whom, and knows who relies on whom to use.

It is worth noting that some problems are broken down into several small problems that must be solved in turn, that is, to solve the second small problem, the calculation results of the first small problem must be used, and so on, until the final answer to the question is calculated.