8下数学第一,二章总结（The first in math, chapter two）.doc

8下数学第一,二章总结（The first in math, chapter two） The eighth grade mathematical summary The first chapter is one dollar inequality and one dollar inequality group One. Inequality 1. Using the symbol (or less than or equal), the (or greater than) connection is called an inequality. 2. (1) non-negative = greater than or equal to 0 = 0 and positive = not less than 0 (2) non-positive = 0 = 0 and negative = no greater than 0 The basic properties of inequality 1. Add (or subtract) the same integral to both sides of the inequality, which means that if a b, then a + c b + c, a-c b-c. 2. Multiply both sides of the inequality by (or divide by) the same positive number, and the inequality is the same, that is, if a b, and c 0, ac BC. 3. Multiply both sides of the inequality by (or divide by) the same negative number, the direction of the inequality change, that is, if a BBB 0 b, and c 0, ac BC, then. Iii. Solution set of inequalities 1. The value of the unknown quantity which can make the inequality, is called the solution of the inequality; All solutions of an inequality, the solution set of this inequality; The process of solving a set of inequalities is called the solution inequality. 2. The solution of the inequality can have many, many, many, in a certain range, different from the solution of the equation. 3. The solution set of the inequality is expressed on the number line: When the solution set of the inequality is represented by a number line, the boundary and direction must be determined. Boundaries: the equals sign is a solid circle, not an equal sign is a hollow circle; Direction: big to right, small left. Four. One dollar an inequality There is only one unknown, and the number of unknowns is the integral, the number of unknowns is one, and the inequality like this is called a one-dimensional inequality. 2. The process of unary an inequality is similar to solving a single equation, especially if the inequality is multiplied by or divided by a negative number, t