Mathematics knowledge points in the next period of the first grade 1. 1 positive and negative numbers.
Books that have been studied before, except 0, are called negative numbers with the minus sign "-"in front of them.
Numbers other than 0 that I learned before are called positive numbers.
The number 0 is neither positive nor negative, it is the dividing line between positive and negative numbers.
In the same question, positive numbers and negative numbers have opposite meanings.
1.2 rational number
1.2. 1 rational number
Positive integers, 0 and negative integers are collectively called integers, and positive and negative fractions are collectively called fractions.
Integers and fractions are collectively called rational numbers.
1.2.2 axis
The straight line that defines the origin, positive direction and unit length is called the number axis.
Function of number axis: All rational numbers can be represented by points on the number axis.
Precautions:
The origin, positive direction and unit length of the (1) axis are indispensable.
⑵ The unit length of the same shaft cannot be changed.
Generally speaking, if it is a positive number, the point representing a on the number axis is on the right side of the origin, and the distance from the origin is a unit length; The point representing the number -a is on the left of the origin, and the distance from the origin is one unit length.
1.2.3 reciprocal
Numbers with only two different symbols are called reciprocal.
Two points representing the opposite number on the number axis are symmetrical about the origin.
Add a "-"sign before any number, and the new number represents the antonym of the original number.
Expanding reading: mathematical problem-solving methods Fill-in-the-blank questions are one of the important questions in standardized tests. Like multiple-choice questions, it has the advantages of clear test objectives, wide knowledge coverage, accurate and fast marking, and is conducive to examining students' analytical judgment and calculation ability. The difference is that the fill-in-the-blank question does not give an answer, which can prevent students from guessing the answer.
In order to solve multiple-choice questions and fill-in-the-blank questions quickly and correctly, in addition to accurate calculation and strict reasoning, there are also methods and skills to solve multiple-choice questions and fill-in-the-blank questions. The following examples introduce common methods.
(1) Direct deduction method: Starting directly from the conditions given by the proposition, using concepts, formulas, theorems, etc. Carry out reasoning or operation, draw a conclusion and choose the correct answer. This is the traditional method of solving problems, which is called direct deduction.
(2) Verification method: find out the appropriate verification conditions from the questions, and then find out the correct answer through verification, or substitute alternative answers into the conditions for verification to find out the correct answer. This method is called verification method (also called substitution method). This method is often used when encountering quantitative propositions.
(3) Special element method: substitute appropriate special elements (such as figures or numbers) into the conditions or conclusions of the topic, so as to get the solution. This method is called the special element method.
(4) Exclusion and screening method: for multiple-choice questions with only one correct answer, according to mathematical knowledge or reasoning and calculus, the incorrect conclusion is excluded and the remaining conclusions are screened, so that the solution to make the correct conclusion is called exclusion and screening method.
(5) Graphic method: According to the nature and characteristics of the graphics or images that meet the conditions of the topic, make a judgment and make a correct choice, which is called graphic method. Graphic method is one of the common methods to solve multiple-choice questions.
(6) Analysis method: directly through the conditions and conclusions of multiple-choice questions, make detailed analysis, induction and judgment, so as to select the correct result, which is called analysis method.