Using letters to express the meaning of numbers: it is helpful to the essential characteristics of concepts and can make the relationship between numbers more concise and universal. Simplify the thinking process and easily form a conceptual system.

note:

1. When a number is represented by a letter, the number is multiplied by the letter, and the letter is multiplied by the letter, and the multiplication sign in the middle can be omitted. Or ""(dot).

2. When multiplying letters and numbers, omit the multiplication sign and put the numbers in front of the letters.

3. When there is division, it is expressed by fraction.

4. If the result includes addition and subtraction, add "()" to the unit.

5. When the coefficient is a fraction, the fraction should become a false fraction.

For example:

Multiplication and distribution law: (a+b)*c=a*c+b*c

Law of multiplicative association: (a*b)*c=a*(b*c)

Multiplicative commutative law: a * b = b * a

Alphanumeric is the fifth unit of Beijing Normal University Edition-using letters to represent numbers. This is the beginning for pupils to learn algebra knowledge, and it is the transition from pupils' understanding of concrete numbers to abstract numbers. It is also the basis of equation teaching.

Composition of nucleus: X represents the symbol of elements, Z represents the proton number of atoms, and A represents the mass number of atoms.

Letters can represent any number, but only one number can be represented in a question. It can also represent a formula with a specific meaning, a certain number that meets the conditions, or even a number with a certain law. In short, letters can concisely express quantitative relations. For example: a can represent a set; F(x) represents the function of x and so on. Representing numbers by letters is a great development in the history of mathematics.

Father of algebra? Vedas

The first person who used letters to represent numbers was the French mathematician Veda. David devoted his life to mathematical research and made many important contributions, becoming the greatest mathematician of that era. Since David's system used letters to represent numbers, it has led to a lot of mathematical discoveries and solved many complicated problems in ancient times. Vedas, an outstanding French mathematician. He was a lawyer when he was young, and later devoted himself to mathematics research. He was the first to consciously and systematically use letters to represent known numbers, unknowns and their powers, which brought great progress in algebraic theory research. He discussed various rational transformations of the roots of the equation and found the relationship between the roots of the equation and the coefficients, so people called the conclusion describing the relationship between the roots and coefficients of a quadratic equation in one variable "Vieta Theorem" and was known as the "father of algebra" in Europe. In the war between France and Spain, the Vedas successfully cracked the Spanish military code by ingenious mathematical methods, and won the war initiative for their motherland.