1, positive and negative numbers. Positive and negative numbers are a way to express numerical relations, reflecting the differences in quantity and direction of things described.
2. rational number. Rational number is the collective name of integer (positive integer, 0, negative integer) and fraction, and it is the set of integer and fraction.
3. Scientific counting method and approximate value. Scientific notation: numbers greater than 10 are recorded as ax10 n, where a is a number with only one integer and n is a positive integer. This notation is called scientific notation. Proximity number: the closeness between approximation number and exact number, which can be expressed by precision.
4. Algebraic expressions. Algebraic expression is a general term for monomial and polynomial, and it is a part of rational formula.
5. One-dimensional linear equations and properties of equations. There is only one unknown, and the number of unknowns is 1 (times). Such an integral equation is called a one-dimensional linear equation.
6. Preliminary geometry. Some geometric figures are not all on the same plane, they are three-dimensional figures.
7. Straight ray line segment. Straight line: there are no endpoints at both ends, which can extend to both ends indefinitely, and the length cannot be measured. Ray: a line drawn from one end and extending indefinitely from the other, the length of which cannot be measured. Line segment: both ends have endpoints, and it is not allowed to extend to both sides. The length can be measured.
8. Understanding from the angle. Features of an angle: a vertex and two sides (straight). The size of the angle: it is related to the size of both sides, and has nothing to do with the length of both sides.
The importance of learn mathematics:
1. Mathematics is closely related to our life. To say that the real effect of learning mathematics is not reflected in exam-oriented education, but in my own thinking about the future.
2. The importance of mathematics is self-evident. Mathematics is the foundation of all sciences and an important channel to cultivate logical thinking. It can be said that every major progress of our mankind is strongly supported by mathematics.
3. The application of mathematical knowledge in life is everywhere. From the calculation of daily living costs, to astronomy, geography, quality control, agricultural economy, aerospace, there are shadows of using mathematics.