What does variation mean in mathematics? What is a variant ?

By changing the manifestation of the non-essential characteristics of similar things, changing the angle and method of observing things, the variant highlights the essential characteristics of things, highlights the hidden essential elements, and allows students to think in the variant, so as to grasp the essence and laws of things.

Variation refers to the form of expression formed by changing the non-essential characteristics of an object to highlight the essential characteristics of the object. It refers to changing the essential characteristics of an object to highlight the non-essential features of the object, thus showing that the connotation of the concept has changed. The presentation of the topic often "hides" the essential attributes of the special key to solving the problem in the non-essential attributes, and the teacher has to inspire the students to reveal the essential attributes from the non-essential attributes step by step.

This necessitates the application of the law of variation. Variation is the manifestation of the non-essential characteristics of the object by changing it, so that students can think in the variation, so as to grasp the essence and rules of things

Conditionals can be changed, conditional operations can be changed, numerical values can be changed, constants can be changed into variables, etc. It is also possible to change the conclusion (or what is sought). Under the premise that the method remains the same, different changes are made to the conditions or requirements, so as to master multiple problems and one solution, grasp the essence of thinking, and achieve the purpose of improving thinking.

The variation is different from the original, ** from the original, it is a transformation of the original form, and it is generally done to be closer to the answer than the original form.

Usually it is a variation of a certain question, but some of the conditions have been changed, the method of doing the question has not changed, or the amount of requirements has changed, but in short, it is not the essential attribute of the question type.

By changing the manifestation of the non-essential characteristics of similar things, changing the angle and method of observing things, the variant highlights the essential characteristics of things, highlights the hidden essential elements, and allows students to think in the variant, so as to grasp the essence and laws of things.

A simple explanation of the variant.

One refers to the form of expression formed by changing the non-essential characteristics of the object to highlight the essential characteristics of the object.

The second refers to the change of the essential characteristics of the object to highlight the non-essential characteristics of the object by Bichai, so as to show that the connotation of the concept has changed.

The presentation of the topic often "hides" the essential attributes of the special key to solving the problem in the non-essential attributes, and the teacher has to inspire the students to expose the essential attributes step by step from the non-regretful essential attributes. This necessitates the application of the law of variation. Variation is the manifestation of the non-essential characteristics of the object by changing it, so that students can think in the variation, so as to grasp the essence and laws of things.

A brief analysis, the song is detailed and forgiving, as shown in the picture of the wild judgment.

Since there is only one green at most, it is divided into two situations:

If there is 1 green card, the possibility is c(4,1)*c(12,2)=4*66=264 kinds, that is, 1 for 4 greens, and 2 for 12 other colors;

Without green, first of all, 3 colors are not considered to be homocoloric, and the probability is c(12,3)=220;

Considering the same color situation, that is, there are 3 possibilities: all red, all yellow, all blue, each case is 4 to take 3 cards, that is, c(4,3), and its cumulative probability is 3*c(4,3)=12;

The total number of possibilities without green is: Possibility of not considering the same color - Possibility of the same color = c(12,3)-3c(4,3) = 208 Likelihood of having 1 green card + Probability of not having green = 264 + 208 = 472 types.

Permutations and combinations pay attention to simplifying conditions, transforming cumbersome conditions into a single module.

Variant 1 has a problem with parsing - c(12,2) doesn't guarantee that the other 2 cards are of different colors. The correct solution is as follows:

Up to 1 green card contains up to 2 situations:

1) There is 1 green card, and there is a c(4,1). Then 2 of the remaining 3 colors are taken, and there are c(3,2)c(4,1)c(4,1). According to the principle of multiplication, there are a total of :

c(4,1)c(3,2)c(4,1)c(4,1)=4×3×4×4

192 species. 2) If no green is taken, the remaining 3 colors are taken, including c(4,1)c(4,1)c(4,1)c(4,1).

64 species. According to the principle of addition, the common share that satisfies the conditions:

192 + 64 = 256 species.

The knowledge of high school mathematics is difficult, so if you want to solve a problem, you must figure out the context of his blue dragon, and practice makes perfect for future use.

<> I hope you can be fierce and wheely, and if you don't understand, you can ask the branch. Shed rotten thank you.