# Who introduced the symbol $\sqrt {x}$?

The question is already in the title.
I am interested in who was the first to introduce the symbol $\sqrt {.}$
I was asked this question from one of my students -since as he said the symbol is bizarre-
If it is possible I would also like to see other notations that have been used for square roots through time. Thanks in advance!

• This question is answered here hsm.stackexchange.com/questions/2264/… The radix symbol, without the overbar, was first used by Rudolff in 1525, the overbar was added by Descartes in La Geometrie (1637). – Conifold Oct 21 '15 at 18:58

## 1 Answer

The easiest way is to check on this site :

Square root. The first use of a capital R with a diagonal line was by Leonardo of Pisa (or Fibonacci) :

The first appearance of the abbreviation R or R(with line) for radix is in his Pradica geometriae (1220), where one finds the R meaning "square root" in an expression "et minus R. 78125 dragme, et diminuta radice 28125 dragme."(Cajori vol. 1, page 90).

The radical symbol first appeared in 1525 in Die Coss by Christoff Rudolff (1499-1545). He used the symbol (without the vinculum) for square roots. He did not use indices to indicate higher roots, but instead modified the appearance of the radical symbol for higher roots.

The fundamental work on these topics is still :