√ Mathematically called "root sign", which means to find the arithmetic square root of a number. (that is, the square is equal to the positive number of this number). Negative numbers have no arithmetic square root. The arithmetic square root of the real number A is denoted as √a, where a≥0 is defined as √a≥0.

The root sign is a symbol used to represent the root operation of a number or an algebra. If a? =b, then A is the n-th root of B or A is the 1/n power of B. The n-th handwritten and printed characters are represented by, and the number of roots or algebraic expressions are written in the area surrounded by the left side of the symbol and the right side of the horizontal part above the symbol, which cannot be out of bounds.

Radical multiplication and division rule:

1. Multiply (divide) the same root and multiply (divide) the coefficient before the same root as the coefficient of product (quotient); Multiply (divide) the root number into the root number and then replace it with the simplest root.

2. Heterogeneous root multiplication (division) should be converted into the same root first, and then operated according to the same root multiplication (division) law.

Addition and subtraction of roots: to add and subtract each root, we must first turn the root into the simplest root, and then merge the same roots. Quadratic root addition and subtraction: first simplify each quadratic root into the simplest quadratic root, and then merge similar quadratic roots respectively.