### Ellipsis (i.e., `three dots')

Ellipsis (three dots) is produced in mathematics mode using
the control sequences `\ldots`

(for dots aligned
with tbe baseline of text), and `\cdots`

(for dots
aligned with the centreline of mathematical formulae). Thus
the formula

is obtained by typing
\[ f(x_1, x_2,\ldots, x_n) = x_1^2 + x_2^2 + \cdots + x_n^2 \]

Similarly the formula

is produced using `\cdots`

, by typing
\[ \frac{1 - x^{n+1}}{1 - x} = 1 + x + x^2 + \cdots + x^n \]