2. Set and its elements are two different concepts, which are given by description in textbooks, similar to the concepts of points and lines in plane geometry.
3. The elements in a set are deterministic (a.a and a: a must be one of them), different from each other (if a: a and b: a, then a≠b) and disordered ({a, b} and {b, a} represent the same set).
4.Set has two meanings, that is, all eligible objects are its elements, and as long as they are its elements, conditions must be signed.
5. Representation methods of sets: enumeration method, description method and graphic method are commonly used.
Set and function
Content intersection and complement set, and power exponential pair function. Parity and increase and decrease are the most obvious observation images.
When the compound function appears, the law of property multiplication is distinguished. To prove it in detail, we must grasp the definition.
Exponential function and logarithmic function are reciprocal functions. Cardinality is not a positive number of 1, and 1 increases or decreases on both sides.
The domain of the function is easy to find. Denominator cannot be equal to 0, even roots must be non-negative, and zero and negative numbers have no logarithm.
The tangent function angle is not straight, and the cotangent function angle is uneven; The real number sets of other functions have intersection in many cases.
Two mutually inverse function have that same monotone property; The images are symmetrical with Y=X as the symmetry axis.
Refer to the above content: Baidu Encyclopedia-High School Mathematics