Question

A? ________ is an arrangement of r objects chosen from n distinct objects without repetition and without regard to order

Answer 1

If we do not care about order, then a combination is an arrangement of r objects chosen from n distinct objects. It can often be seen written as:

$^{n}C_r$ or $\left(\begin{array}{cc}n\\r\end{array}\right)$

Its factorial form is:

$^{n}C_r = \frac{n!}{r!(n - r)!}$