2. Natural numbers): 0 and positive integers are called natural numbers. Numbers like 0, 1, 2, 3, 4, 5, 6, ... are natural numbers.
3. Even number: an integer divisible by 2. Even number =2k, where k is an integer.
4. Odd number: an integer that is not divisible by 2. Odd number =2k- 1, where k is an integer.
5. Score: Divide the unit "1" into several parts on average, and the number representing such one or several parts is called a score. The horizontal line in the middle of the score is called fractional line, the number above the fractional line is called numerator, and the number below the fractional line is called denominator. Just think of it as division, and divide the numerator by the denominator (because 0 can't be divided in division, the denominator can't be 0).
6. Decimal: Decimal consists of integer part, decimal part and decimal point. When measuring an object, it is often not an integer, so the ancients invented decimals to supplement integer decimals, which is a special form of fractional fractions. Fractions with denominators of 10, 100, 1000 ... can be expressed in decimals. Any decimal can be converted into finite decimal or infinite cyclic decimal, but infinite acyclic decimal in decimal cannot be converted into component number.
7. Prime number: also called prime number, a positive integer greater than 1. There are no other factors except 1 and itself.
8. Rational number: it is a general term for integers and fractions, and all rational numbers can be converted into component numbers. Any rational number can be written as a fraction m/n (m, n is an integer, n≠0).
9. Irrational number: it is an infinite cycle decimal. That is, the real number of irrational numbers cannot be written as the ratio of two integers. Most common irrational numbers are square root, π and E, etc.
10. Real number: it can be divided into rational number and irrational number, or algebraic number and transcendental number, or positive real number, negative real number and zero. Mathematically, real numbers are intuitively defined as numbers corresponding to points on the number axis. A set of real numbers is usually represented by the letter r or r n, and r n represents an n-dimensional real number space. Real numbers are uncountable.
1 1. Function: It is a correspondence, which means that each input value corresponds to a unique output value. The standard symbol of the output value x corresponding to the input value in the function f is f(x). By definition, we can say that there are two variables X and Y in a certain change process. According to certain correspondence rules, a given X corresponds to a uniquely determined Y, so Y is called a function of X, where X is an independent variable and Y is a dependent variable. At the same time, we can also define it as follows: Generally speaking, given a set of non-empty numbers A and B, any element X in A has a unique Y in B according to a certain correspondence rule F, then this correspondence from set A to set B is called a function from set A to set B. Note: x → y = f (x), x ∈ a} Set A is called the domain of the function, D, and
I hope the above can help you.