People's education edition, the first important knowledge point of mathematics, 1. Rational number:
(1) Any number that can be written in form is a rational number. Positive integers, 0 and negative integers are collectively referred to as integers. Positive and negative scores are collectively called scores; Integers and fractions are collectively called rational numbers. Note: 0 is neither positive nor negative; -a is not necessarily negative, and +a is not necessarily positive; P is not a rational number;
(2) Classification of rational numbers: 122. Number axis: The number axis is a straight line that defines the origin, positive direction and unit length.
2. The opposite number:
(1) There are only two numbers with different signs, and we say that one of them is opposite to the other; The antonym of 0 is still 0;
(2) Is the sum of opposites 0? a+ b=0？ A and b are opposites.
3. Absolute value:
(1) The absolute value of a positive number is itself, the absolute value of 0 is 0, and the absolute value of a negative number is its inverse; Note: The absolute value means the distance between a point on the number axis and the origin.
(2) The absolute value can be expressed as: or; The problem of absolute value is often discussed in categories;
4. Rational number ratio:
(1) The greater the absolute value of a positive number, the greater the number; (2) Positive numbers are always greater than 0 and negative numbers are always less than 0; (3) Positive numbers are greater than all negative numbers; (4) Two negative numbers are larger than the size, but the absolute value is smaller. (5) Two numbers on the number axis, the number on the right is always greater than the number on the left: (6) Large number-decimal 0, decimal-large number 0.
5. Countdown:
Two numbers whose product is 1 are reciprocal; Note: 0 has no reciprocal; If a0, the reciprocal is; If ab= 1? A and b are reciprocal; If ab=- 1? A and b are negative reciprocal.
Basic knowledge of mathematics in grade one, multiplication
The operation of finding the product of n identical factors is called power, and the result of power is called power. In, a is called the base and n is called the exponent. When an is regarded as the result of the n power of a, it can also be read as the n power of a. ..
The odd power of a negative number is negative and the even power of a negative number is positive.
Any power of a positive number is a positive number, and any power of a positive integer is 0.
Operation sequence of rational number mixed operation:
(1) first power, then multiply and divide, and finally add and subtract;
(2) unipolar operation, from left to right;
(3) If there are brackets, do the operation in brackets first, and then press brackets, brackets and braces in turn.
Second, scientific symbols.
Numbers greater than 10 are expressed in the form of a× 10n (where a is a number with only one integer and n is a positive integer), and scientific notation is used.
Use scientific notation to represent n-bit integers, where the exponent of 10 is n- 1.
Three. Approximation and significant figures
A number that is close to the actual number but still different from the actual number is called a divisor.
Accuracy: an approximate value is rounded to the nearest place, so it is accurate to the nearest place.
From the first non-zero digit to the last digit on the left of a number, all digits are valid digits of this number.
For the number a× 10n expressed by scientific notation, its effective number is specified as the effective number in A. ..
Analysis of the key and difficult points of junior high school mathematics 1 senior high school entrance examination. Functions (linear function, inverse proportional function, quadratic function) account for about 15% of the total score.
Quadratic function, in particular, is the key and difficult point of the senior high school entrance examination. It will appear in filling in the blanks, selecting topics and solving problems, with many knowledge points and changeable questions.
Moreover, the last two questions in the test paper usually have a solution, and the general quadratic function and the images and properties of quadratic function, as well as the triangle and quadrilateral synthesis questions are difficult to apply. There is a certain difficulty.
If you don't master this link well, it will directly affect the algebra foundation and have a great influence on the results of the senior high school entrance examination.
2. Simplification of algebraic expressions, fractions and quadratic roots.
Algebraic expression operation, factorization, quadratic root, scientific counting and fractional simplification are the key points of junior high school learning, which run through the whole junior high school mathematics knowledge and are the basis of our mathematical operation, among which factorization and understanding the relationship between factorization and algebraic expression multiplication and fractional operation are difficult.
The senior high school entrance examination generally appears in the form of multiple-choice questions and fill-in-the-blank questions, but it is the basis for solving complete answers. The proficiency of computing ability is directly related to the correct rate of answering questions. If you don't master it well, the correct answer rate will not be very high, and then you can't learn the following equations, inequalities and functions well.
3. The application questions in the senior high school entrance examination account for about 30% of the total score.
Including equation (group) application, linear inequality (group) application, function application, triangle solution application and probability statistics application.
Generally, there will be two or three answers (about 30 points) and two or three multiple-choice questions and fill-in-the-blank questions (10-15 points), accounting for about 30% of the total score of the senior high school entrance examination.