I. Inequality

1, the formula that indicates the relationship between size with less than sign or greater than sign is called inequality.

2. The value of the unknown quantity that makes the inequality valid is called the solution of the inequality.

3. The range of value of x that can make inequality hold is called the solution set of inequality, or simply the solution set.

4. There is an unknown number, and the number of unknowns is 1, which is called one-dimensional linear inequality.

Second, the square root

1. If the square of a positive number X is equal to A, then this positive number X is called the arithmetic square root of A, and 2 is the root index.

2. The arithmetic square root of a is pronounced as "root number A", and A is called the root number.

The arithmetic square root of 3.0 is 0.

If the square of a number is equal to a, then this number is called the square root or quadratic root of a. ..

The operation of finding the square root of a number is called square root.

Third, the cube root

1. If the cube of a number is equal to A, then this number is called the cube root or cube root of A. ..

2. The operation of finding the cube root of a number is called root extraction.

Fourth, the vertical line

1. When two straight lines intersect and one of the four corners is a right angle, the two straight lines are perpendicular to each other. One of the straight lines is called the perpendicular of the other straight line, and their intersection point is called the vertical foot.

2. Draw a vertical line from a point outside the line to the line. The line segment between this point and the vertical foot is called the vertical line segment.

3. The vertical line segment is a part of the vertical line. It is a line segment with a point at one end and a vertical foot at the other.