1. Definition of linear equation with one variable (including only one unknown, the exponent of the simplified unknown is 1, and the coefficient of the unknown cannot be zero)
2. Add and subtract a number or the same algebraic expression on both sides of the equation at the same time, and the solution of the equation remains unchanged.
3. Both sides of the equation are multiplied or divided by a non-zero number, and the solution of the equation remains unchanged.
4. Steps to solve a linear equation with one variable: remove the denominator; Remove the brackets; Transposition; Merge similar projects; The coefficient of the unknown is 1.
5. Pay attention to the relationship among reciprocal, reciprocal and similar items. There are also problems with this chapter.
Chapter II Binary Linear Equations
1. Definition of binary linear equation (including two unknowns, the number of which is 1)
2. Solution of binary linear equation: substitution elimination method, addition and subtraction elimination method.
Chapter III Polygons
1. the relationship between the inner angles of the triangle
The sum of the internal angles of the (1) triangle is equal to 180.
(2) Any external angle of a triangle is equal to the sum of its two non-adjacent internal angles.
(3) The outer angle of a triangle is larger than any inner angle that is not adjacent to it.
(4) The sum of the external angles of the triangle is 360.
2. Classification of angles
(1) classified by angle
Acute triangle: all three angles are acute.
Right triangle: It has a right angle and two acute angles.
Obtuse triangle: It has an obtuse angle and two acute angles.
Classification of equilateral triangles isosceles triangles (including equilateral triangles)
3. Trilateral relationship of triangle
The sum of any two sides of a (1) triangle is greater than the third side.
(2) The difference between any two sides of a triangle is less than the third side.
4. Related attributes of polygons
The sum of the internal angles of (1)n polygons is (n-2) * 180.
(2) The sum of the external angles of any polygon is 360.
(3) The outer angle of a regular N-polygon is 360 /n n n.
(4)n polygons are unstable (n >；; 3)
(5) Triangle is stable.
5. Lay the floor with regular polygons
(1) The floor can cover the same regular polygon: regular triangle, square and regular hexagon.
(2) Use all kinds of regular polygons to lay the floor for the same reason as written in the textbook.
Chapter IV Axisymmetry
1. Axisymmetric: Fold the graph along a straight line. If it can overlap with another graph, then the two graphs are symmetrical about this straight line.
2. The corresponding points in two graphs are called symmetry points about this line and symmetry axes, and the symmetry of two graphs about this line is also called symmetry axes.
3. Axisymmetric figure: If a figure is folded in half along a straight line and the parts on both sides of the straight line can overlap each other, then this figure is called an axisymmetric figure, and this straight line is its axis of symmetry.
4. The distance between the point on the vertical line of the line segment and the two endpoints of the line segment is equal.
5. If a graph is symmetrical about a straight line, then the perpendicular line connecting the symmetrical points is not the symmetry axis of the graph.
6. If the straight line connecting the corresponding points of two graphs is vertically bisected by the same straight line, then the two graphs are symmetrical about this straight line.
7. Two figures are symmetrical about a straight line. If their corresponding line segments or extension lines intersect, then the intersection point is on the axis of symmetry.
8. Axisymmetric is two figures, and axisymmetric figure is one figure.
9. Axisymmetric and axisymmetric figures have axes of symmetry. If an axisymmetric figure is regarded as a whole, it is an axisymmetric figure. If an axisymmetric figure is divided into two parts along the axis of symmetry, then the two figures are symmetrical about this line.
Chapter five. A rudimentary knowledge of statistics