négyzetsgyökjel

The négyzetsgyökjel, often referred to as the radical symbol or square root symbol, is a mathematical sign used to denote the principal, or non-negative, square root of a number. Its origin can be traced back to the 16th century, though its exact etymology is debated. Some scholars suggest it derives from the letter 'r', an abbreviation for the Latin word 'radix', meaning root. Others propose it evolved from a stylized representation of a checkmark or a similar mark used for affirmation.

In its current form, the symbol consists of a hook-like stroke extending from a horizontal bar, with a vertical line at the beginning. The number or expression under the horizontal bar is known as the radicand. For instance, in the expression √9, the number 9 is the radicand, and the symbol indicates that we are looking for a number which, when multiplied by itself, equals 9. The principal square root of 9 is 3, as 3 * 3 = 9.

The négyzetsgyökjel is fundamental in algebra, geometry, and calculus, appearing in equations, formulas, and proofs. It is crucial for solving quadratic equations, calculating distances, and understanding concepts in trigonometry and beyond. While primarily associated with square roots, the symbol can be adapted with an index to represent roots of higher orders, such as the cube root (³√) or fourth root (⁴√). The absence of an index conventionally implies a square root.