√ 1—20:√ 1= 1,√2= 1.4 14,√3= 1.732,√4=2,√5=2.236,√6=2.449,√7=2.645,√8=2.828,√9=3,√ 10=3. 162, √ 1 1=3.3 16,√ 12=3.464,√ 13=3.605,√ 14=3.74 1,√ 15=3.872,√ 16=4, √ 17=4. 123,√ 18=4.242,√ 19=4.358,√20=4.472。
Extension:
The root sign, a mathematical symbol, is a symbol used to represent the root operation of a number or an algebraic expression, which is represented by "√". The radical sign or algebraic expression is written in the area surrounded by symbols and cannot be crossed. If a? =b, then a is the n-th root of b or a is the 1/n power of b.
In modern times, we are used to using the root sign (such as √). ), and feel simple and convenient. At the same time, some people use the capital r of the first letter of the Latin root of the word "root" to indicate the square operation, and then use the first letter q of the Latin word "square" or the first letter c of the "cube" to indicate how many times the square has been opened.
It was not until17th century that the French mathematician Descartes (1596 ~ 1650) first used the radical sign "√ ~". In a book, Descartes wrote: "If you want to find the square root of n, write it;" If you want to find the cube root of n, just write. " Sometimes there are many terms in the square root. In order to avoid confusion, Descartes connected these terms with a horizontal line, and added the root sign √ ~ in front of it (but there is a small hook more than Rudolph's root sign), which is the current root sign form.
Cubic root symbols appeared very late, and it was not until the eighteenth century that we saw the use of symbols in a book, such as the cube root of 25. Later, such as √ ~, radical symbols gradually began to be used.
This shows how difficult it is for a symbol to be widely used. It is the result of continuous improvement, selection and elimination for a long time. It is the crystallization of the collective wisdom of mathematicians, not invented by one person out of thin air, and will never fall from the sky.