Obviously, if we know one of these two square roots, then we can get the other square root according to the concept of reciprocal in time.

If the square of a number is equal to a, then this number is called the square root of a, and the square root of 0 is 0. Negative numbers cannot be squared in the range of real numbers, and square roots can only be opened in the range of positive numbers. For example, the square root of-1 is I and the square root of -9 is 3i.

Square root contains arithmetic square root, which is a kind of square root.

Square root and arithmetic square root are only non-negative numbers.

The number of roots is the power in power operation.

The square root can be obtained by inverse square operation.

Square root: the operation of finding the square root of a non-negative number is called square root, where a is called square root.

If the square of x equals a, then x is called the square root of a, that is, √ a = X.

Analysis of key points and difficulties

This section focuses on the concepts of square root and arithmetic square root. Square root is the basis of square root operation and the preparatory knowledge for introducing irrational numbers. A correct understanding of the concept of square root is helpful to the understanding of symbolic representation, which is the premise of correct square root operation and directly affects the learning of quadratic roots. The teaching of arithmetic roots is not only the focus of this chapter, but also the focus of mathematics learning in the future. The radical operation to be learned later is, in the final analysis, the operation of arithmetic roots, and non-arithmetic roots should also be transformed into arithmetic roots.

The difficulty of this section is the difference between square root and arithmetic square root. First of all, these two concepts are easily confused, and it is not easy for students to distinguish the meanings of their respective symbols. In teaching, we should grasp the positive one of the square root of arithmetic, make clear the meaning of each symbol and distinguish the difference between the two representations. For the square root operation, it is more than just a number.

3. The main contents of this section are square root and arithmetic square root. Pay attention to the simplicity of numbers, and the key is to let students understand the concepts. In addition, pay attention to the strict specification of language when describing words.

Knowledge induction: If the square of a positive number is equal to A, then this positive number X is called the arithmetic square root of A, and A is called the square root.