Root sign and square are reciprocal operations, and we can often get its square from a number. But in real life, what we want is to know a number whose square is equal to this number, which involves the root.

Prescription is suitable for irrational numbers, which is closely related. Having said that, we have to mention the Pythagorean school. The new concept of harmony in this school is that everything can be expressed by the ratio between integers.

A mathematician of this school said when using Pythagorean theorem that the square of 65438+0+the square of 65438 +0 =2, and the number whose square equals 2 cannot be expressed as the ratio between integers. This has shaken the core idea of this school and caused ideological confusion. In order to maintain the reputation and status of the Sect, the school executed mathematicians.

Later, we know that numbers are divided into rational numbers and irrational numbers. The ratio between integers is rational, and vice versa.

The root sign is square, and the square is used in turn, but there may be two results, one positive and one negative.