Vinculum (symbol)
A vinculum is a horizontal line put over a mathematical expression. It shows that it belongs together as a group. (Vinculum is Latin for "chain".)
Examples are:
1. groups of digits repeating forever, for example,
- [math]\displaystyle{ \frac{1}{3} = 0.333333\dots = 0.\overline{3} }[/math]
2. fractions
- [math]\displaystyle{ \frac{500}{10 \times 10} = \frac{5}{1} = 5 }[/math]
3. radicals (in the following example the quantity [math]\displaystyle{ ab+2 }[/math] is the radicand, and thus has a vinculum over it):
- [math]\displaystyle{ \sqrt[n]{ab+2} }[/math]