Simply put: the root sign means that the number in the root sign is equal to the product of those two numbers.

For example, the root number 9 is equal to the product of two 3s or two minus 3s. The root number 4 is equal to the product of two twos or two minus twos.

The number in the junior middle school root number is greater than or equal to 0, because it is meaningful.

The number in the root number of high school can be negative because of the introduction of imaginary number.

Don't worry, little brother! ! ! ! ! ! ! ! ! You won't learn negative numbers until junior high school, and then you will understand them naturally. You can't learn imaginary numbers until high school.

But it doesn't matter if you don't understand now. If you know a little now, you will be better than other peers! ! ! Come on!