There are many kinds of relative numbers, which can be divided into two types according to their manifestations: one is the nominal number, that is, the relative number calculated by comparing two absolute numbers or averages with different properties and connections, which are generally nominal numbers and use more units of measurement. The other is the unknown, which can be multiplied or multiplied according to different situations.

, coefficient, percentage, thousandth, etc. , such as birth rate, mortality rate, etc.

Algebraic meaning of the opposite number: two numbers whose sum is 0 are opposite to each other. The antonym of 0 is still 0. 1, only two numbers with different symbols are called antonyms. A and -a are a pair of opposites, A is called the inverse of -a, and A is called the inverse of A ... Note: -a is not necessarily a negative number. A is not necessarily a positive number. (A is not equal to 0)2. If two real numbers A and B satisfy B =-A. Suppose B is the antonym of A.3.. Two opposite real numbers a and b must satisfy a+b=0. It can also be said that the real numbers A and B satisfy a+b=0, then these two real numbers A and B are the opposite number 4 and Y of a real number X, which is actually a mapping from R to R: Y = f (x) =-X. From the perspective of two-dimensional space, this mapping can be regarded as a rotation (180 degrees) mapping (the center is symmetrical); This mapping can also be regarded as a flip (180 degrees) mapping (axisymmetric); X=0 is the fixed point under this mapping. Geometric meaning: 1, the geometric meaning of the opposite number

On the number axis, two numbers represented by two points with the same distance from both sides of the origin are opposite numbers. 2. On the number axis, two points with opposite numbers (except 0) are located on both sides of the origin and are symmetrical about the origin. 3. At this point, the inverse number of b is ﹣b=﹣(﹣a)=a, then we say that "the inverse number has mutual symmetry".