Integer is one of the basic concepts in mathematics, including positive integer, negative integer and zero. Junior high school mathematics needs to master the concepts of four integer operations, absolute value and antonym.

1. Four operations

The four operations of integers include addition, subtraction, multiplication and division. The operations of addition and multiplication are the same as those of natural numbers, and the operations of subtraction and division need to pay attention to the sign change.

For example: $5-(-3)=5+3=8$, $(-4)\div2=-2$, $(-4)\div(-2)=2$.

2. Absolute value

The absolute value is the distance between a number and zero, which is represented by the symbol $|x|$. When $x$ is positive, $ | x | = x $ When $x$ is negative, $|x|=-x$.

For example: $|-3|=3$, $|5|=5$.

3. Inverse number

The inverse of a number is a number with equal absolute value but opposite sign. Represented by the symbol $-x$.

For example, $-(-3)=3$, the antonym of $-5$ is 5$.

Second, the score.

Fraction is also one of the basic concepts in mathematics, which consists of numerator and denominator. Junior high school mathematics needs to master the concepts of simplification, comparison size and four operations of fractions.

1. Simplify

To simplify a fraction into the simplest form is to divide the numerator and denominator by their common factors at the same time, so that the numerator and denominator of the fraction have no other common factors.

For example, $\frac{ 12}{ 16}$ can be simplified to $\frac{3}{4}$, and $\frac{6}{9}$ can be simplified to $\frac{2}{3}$.

Comparative size

When comparing the sizes of two fractions, you can change them into fractions with the same denominator and then compare their molecular sizes.

For example, $\frac{ 1}{2}$ and $\frac{3}{4}$ can be compared with $\frac{2}{4}$ and $\frac{3}{4}$ because they have the same denominator, so $

3. Four operations

The four operations of fractions include addition, subtraction, multiplication and division. The operations of addition and multiplication are the same as those of natural numbers, and the operations of subtraction and division need to pay attention to the general division and approximate division of fractions.

For example: $ \ frac {1} {2}+\ frac {1} {3} = \ frac {5} {6} $,$ \ frac {2} {3} \ div \ frac {4} {5} 4} {5.

Third, algebraic expressions.

Algebraic expressions are expressions composed of numbers, letters and operational symbols. Junior high school mathematics needs to master the concepts of algebra simplification, expansion and factorization.

1. Simplify

Simplifying algebraic expressions means merging similar items in algebraic expressions to make the expressions more concise.

For example, 2x+3x+5 dollars can be reduced to 5x+5 dollars.

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Expanding algebraic expression refers to expanding the formula in brackets according to the algorithm.

For example, $(x+2)(x-3)$ can be expanded to $ x 2-x-6 $.

3. Factorization

Factorization refers to the decomposition of algebra into the product of several factors.

For example, $ 2x 2+6x $ can be factorized into $2x(x+3)$.

Fourth, the equation

An equation refers to an equation containing unknowns. Junior high school mathematics needs to master the concepts of equation solution, linear equation and quadratic equation.

1. Solution

Solving an equation refers to finding the value of an unknown quantity that makes the equation hold.

For example, the solution of $2x+3=7$ is $x=2$.

2. Linear equation

Linear equation refers to the equation with the highest degree of unknown quantity 1, which can be expressed as $ax+b=0$.

For example, $2x+3=7$ is a linear equation.

3. Quadratic equation

Quadratic equation refers to two unknown equations with the highest degree, which can be expressed in the form of $ ax 2+bx+c = 0 $.

For example, $ x 2-3x+2 = 0 $ is a quadratic equation.

Verb (abbreviation for verb) geometry

Geometry is a branch of mathematics that studies the relationship between space shape, size and position. Junior high school mathematics needs to master the concepts such as the nature of geometric figures, calculation area and volume.

Properties of 1. Geometry

The properties of geometric figures include name, number of edges, angle, symmetry and so on.

For example, a square has four sides, four right angles, symmetry and other properties.

Calculated area

Calculating the area refers to finding the area covered by the plane figure.

For example, the area of a square can be calculated as the square of the side length.

Calculated volume

Calculating volume refers to finding the volume of three-dimensional graphics.

For example, the volume of a cube can be calculated as a cube with a side length of.