Radical Expressions

Algebra 2 students are currently working with radical expressions which use the radical sign. The radical sign for square root was introduced in 1525 by Christoff Rudolff (1499-1545) in his book Die Coss (The Unknown). This was the first German textbook on Algebra. It was one of the earliest printed books to use decimal notation and it also introduced the concept x^0 =1. By the seventeenth century, the radical sign was widely accepted. It is believed that Rudolff used the radical sign because it resembled the lower case “r”, for radix.


Arabic writers used the word “radix” (root) because they thought of a square number growing out of a root or being extracted from a root. Late Medieval writers used the symbol Rx to represent radix. The symbol Rx^2 (for square root) was used in 1484.

~Michelle Greenbaum
Math Instructor