When math symbols were incorporated into primary school textbooks

Math Problems in Renminbi One day, I went to the mall with my mother. Mom went into the supermarket to buy something and asked me to stand at the place where I paid and wait for her. I didn't have anything to do, just watched the salesman and aunt collect the money.

Looking at it, I suddenly found that the money collected by the salesman aunt was 1 yuan, 2 yuan, 5 yuan, 10 yuan, 20 yuan, and 50 yuan, and I felt very strange: why is there no 3 yuan, 4 yuan, 6 yuan, 7 yuan, 8 yuan, 9 yuan or 30 yuan, 40 yuan, 60 yuan? I quickly ran to ask my mother, and my mother encouraged me to say

Use your brain and think about it, Mom believes you can figure out why for yourself. I settled down and thought about it carefully. After a while, I jumped for joy :

I know, because as long as there are 1 yuan, 2 yuan, and 5 yuan, you can form 3 yuan, 4 yuan, 6 yuan, 7 yuan, 8 yuan, and 9 yuan at will, and as long as you have 10 yuan, 20 yuan, and 50 yuan, you can also form 30 yuan, 40 yuan, and 60 yuan, and ......My mother nodded and asked me another question: "If it's just to be able to combine at will, isn't it enough for only 1 yuan?" Why do you need 2 yuan or 5 yuan?

I said, "It's not convenient to use just 1 yuan to form a larger number." My mother smiled with satisfaction, and praised me for being observant and using my brain, and I was more comfortable listening to it than eating my favorite ice cream.

Here, I also want to tell other children: in fact, there are math problems everywhere in life, as long as you can, if not, tell me what grade you have, I am helping you!

Factorial is a high school content, and it is difficult to introduce it to elementary school.

The primary school textbook is the second volume of the fifth grade, and there is a unit of character description. wrote that Lin Daiyu first entered Jiafu, focusing on learning Wang Xifeng's character description techniques.

It shouldn't be culled! Equation thinking is so important!

First, in a broad sense, equations can be used to describe various quantitative relationships in the real world. The core of the idea of equation is to represent the unknown quantities in the problem with mathematical symbols other than numbers (commonly used letters, y, etc.), and construct an equation model according to the equality relationship between the relevant quantities. The idea of equations embodies the unity of the opposition between the known and the unknown, and it is an important part of mathematical construction.

Second, from a small aspect, equations are the main content in the field of elementary mathematical algebra, is the most important means used by junior high school students to solve problems, is an important tool to solve practical problems, equations and arithmetic, because the unknown number participates in the construction of equal relations, it is more convenient for people to understand the problem, analyze the quantitative relationship and build a model, so the equation plays an important role in solving the practical problems based on constants.

3. From the perspective of the problems existing in practical teaching, for example, when we encounter complex application problems, most of us will think of using equations to solve them!

You should learn in elementary school.

Shift method: e.g. x+3=2x-9 solution x=12 Remember to change the sign to move the term with unknown numbers in the equation to the other side of the equation, and don't forget to change the sign when moving the term to the other side of the equation. Another analogy is that from 5x=4x+8 we get 5x - 4x=8 ; Moving the unknowns together, and emphasizing that you must change the previous symbols, I used to make a lot of mistakes in the symbols, removing the denominator, multiplying both sides of the equation by the least common multiple of each denominator, and removing the parentheses, usually first the parentheses, then the middle brackets, and finally the curly braces.

However, the order can sometimes be made easier to calculate, depending on the situation. The property can be assigned according to multiplication.

The discovery of 0 began in India. Around 2000 B.C., the Vedas, the oldest text of ancient Indian Brahmanism, had the symbol "0", which at that time represented the position of nothingness (emptiness) in Indian Brahmanism. Around the beginning of the 6th century, the natal notation was introduced in India.

The great Indian mathematician Glaf of the early 7th century. Magpuda first explained that 0 of 0 is 0, and any number is obtained by adding 0 or subtracting 0. Unfortunately, he did not mention the example of using natal notation to perform calculations.

Some scholars believe that the concept of zero arose and developed in India because of the philosophical idea of "absolute nothingness" in Indian Buddhism.

In 733 AD, an Indian astronomer introduced the Indian notation to the Arabs during a visit to Baghdad, the capital of present-day Iraq, because of its simplicity and ease of use, which soon replaced the Arabic numerals that had preceded it. This system of notation was later introduced to Western Europe.

delta (uppercase δ, lowercase δ) is the fourth Greek letter.

Uppercase δ used for:

In mathematics and science, it represents the change of variables.

In mathematics, in regression analysis, the difference between the measured value (true or accurate) and the value according to the regression equation.

In the unary quadratic equation ax2+bx+c=0(a≠0) or the quadratic function y=ax2+bx+c(a≠0) represents b2-4ac, in the equation, if δ 0, then the equation has a real solution (if δ> 0, then the equation has two unequal real solutions; If δ=0, then the equation has two equal real solutions), and if δ> 0, the image has two intersections with the x-axis; If δ=0, there is only one intersection between the image and the x-axis; If δ< 0, the image has no intersection with the x-axis.

In physics, the amount of change in a physical quantity is described.

For example, q=cmδt

where q represents the heat, c represents the specific heat [capacity] of the substance, m represents the mass of the substance, and δt represents the amount of change in temperature).

Another example is f=kδx (Hooke's law).

where f represents the tensile force, k represents the spring stiffness (stubbornness) coefficient, and δx represents the spring elongation).

Any delta particle in particle physics.

It is the abbreviation of the discriminant formula b 2-4ac in the 2-ary linear equation.

The mathematical symbol "δ" is the abbreviation of the discriminant formula b 2-4ac in the 2 yuan equation, which is the content of the junior high school textbook.

There's a "triangle" and then there's one in physics that's temperature-related.

It is an abbreviation of the discriminant formula b 2-4ac in the two-dimensional equation that can be learned in junior high school.

delta (uppercase δ, lowercase δ) is the fourth Greek letter.

Mathematical symbols were invented and used later than numbers, but they outnumbered numbers. There are now more than 200 commonly used mathematical symbols, and each of them has an interesting experience.

There are too many mathematical symbols to illustrate, such as there:

1. Operator symbols.

For example, the plus sign (+), the minus sign ( ), the multiplication sign ( or ·), the division sign ( or ), the union ( ) intersection ( ) of two sets ( ) the root sign ( logarithm (log, lg, ln, lb), ratio ( :) absolute value sign | |Differentiation (D), integration ( ), closed surface (curve), integration ( ), etc.

2. Relationship symbols.

For example, "=" is an equal sign, " is an approximate sign (i.e., approximately equal to), "is an equal sign," > is a greater than sign, "is less than a sign," is greater than or equal to a sign (can also be written" i.e., not less than), "is less than or equal to a sign (can also be written" "i.e., not greater than)," indicates the trend of variable change, " is a similar sign, " is a full equal sign, " is a parallel sign, " is a perpendicular sign, " is a proportional sign (the reciprocal relation can be used when representing inverse proportionality), "is a belonging sign," is included in the sign, " is the containing symbol, "|means "divisible" (e.g. a|.)b means "a is divisible by b", and ||b means that r is the maximum power of a divisible by b), and any letter such as x, y, etc., can represent an unknown.

3. Combine symbols.

For example, parentheses in parentheses "()" [ curly braces "", dash "—".

4. Nature symbols.

Such as positive sign "+" negative sign"-" plus or minus sign, etc.

5. Omit symbols.

Such as triangles ( ), right triangles (rt), sinoids (sin) (see trigonometric functions), hyperbolic sinoidal functions (sinh), x functions (f(x)), limits (lim), angles ( ) because, so and so on.

6. Permutation and combination of symbols.

c the number of combinations, the number of a (or p) permutations, the total number of n elements, r the number of elements involved in the selection, !Factorial, etc.

7. Discrete mathematical notation.

For example, full quantifiers, existential quantifiers, assertors (the formula is provable in l), satisfies (the formula is valid on e, the formula is satisfied on e), the "not" operation of propositions, such as the negation of propositions is p, the "conjunction" ("and") operation of propositions, the "disjunctive" ("or", "can be combined") operation of propositions, the "conditional" operation of propositions, the "two-conditional" operation of propositions, etc.

In mathematics, we often use some mathematical symbols, such as:

1. Quantity symbols.

i，a，x，e，π。

2. Operational symbols.

For example, the plus sign (+), the minus sign ( ), the multiplication sign ( or ·), the division sign ( or ), the union ( ) intersection ( ) of two sets ( ) the root sign ( logarithm (log, lg, ln, lb), ratio ( :) absolute value sign | |Differentiation (d), integration ( ), closed surface (curve), integration ( ).

2. Operational symbols.

3. Relationship symbols.

For example, "=" is an equal sign, " is an approximate sign (i.e., approximately equal to), "is an equal sign," > is a greater than sign, "is less than a sign," is greater than or equal to a sign (can also be written" i.e., not less than), "is less than or equal to a sign (can also be written" "i.e., not greater than)," indicates the trend of variable change, " is a similar sign, " is a full equal sign, " is a parallel sign, " is a perpendicular sign, " is a proportional sign (the reciprocal relation can be used when representing inverse proportionality), "is a belonging sign," is included in the sign, " is the containing symbol, "|means "divisible" (e.g. a|.)b means "a is divisible by b", and ||b means that r is the maximum power of a divisible by b), and any letter such as x, y, etc., can represent an unknown.

3. Combine symbols.

Such as parentheses "() in parentheses "[ curly braces "".

Fourth, the nature of the symbol.

Such as positive sign "+ "negative sign" - "plus or minus sign" ".

5. Omit symbols.

Such as triangle ( ) right triangle (rt), parallelogram, angle ( ) because, so etc.

A symbol in mathematics. Meaning: Belongs.

This paragraph].

We usually use the uppercase Latin letters a, b, c,...Indicates a set, ,... with lowercase Latin letters a, b, cRepresents an element in a collection.

If a is an element of the set a, then a belongs to the set a, denoted a a; If a is not an element in set A, then A is said not to belong to set A, denoted as A A.

When expressing this symbol mathematically, it can be directly expressed with the word "belongs".

For example, a a can be read as: small a belongs to a large a

The set belongs to a s means that a belongs to the set s; A s means that A does not belong to S. (1/2)−1 ∈ n

2−1 ∉ n

Belong; It doesn't belong.

The meaning of belonging is element A set B,

is the meaning of belonging, indicating subordination, for example: an element belongs to a set, such as 2

Elements belong to collections.

belongs".