Cleverly remember the square root formula 1. Square root formula table
Negative square root is no good, zero square root is still zero.
There are two positive square roots with opposite signs and the same value.
The root finger can be omitted, and the rest must be made clear.
Negative numbers have only odd roots, and the arithmetic square root is zero or positive.
2. 1 to 20 square formula table
1? = 1、2? =4、3? =9、
4? = 16、5? =25、6? =36、
7? =49、8? =64、9? =8 1、
10? = 100、 1 1? = 12 1、
12? = 144、 13? = 169、
14? = 196、 15? =225、
16? =256、 17? =289、
18? =324、 19? =36 1、
20? =400。
The nature of the square root ① If a positive number has a square root, then there must be two, which are reciprocal.
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.
(2) If the square of a positive number X is equal to A, that is, the square of X is equal to A, then this positive number X is called the arithmetic square root of A. The arithmetic square root of A is recorded as "root number A" and A is called the root number.
③ It is stipulated that the square root of 0 is 0.
④ Negative numbers cannot be squared in the range of real numbers, and square roots can only be opened in the range of complex numbers.
For example, the square root of-1 is 1, and the square root of -9 is 3.
⑤ 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 is equal to a, then x is called the square root of a, that is, the positive and negative root sign a= positive and negative X.