Definition:Binomial Coefficient/Technical Note

Definition
The $\LaTeX$ code to render the binomial coefficient $\dbinom n k$ can be written in the following ways:



or:

The  form is preferred on  because it is simpler.

It is in fact an abbreviated form of, which is the preferred construction when   is required for another entity in the expression.

While the form  is valid $\LaTeX$ syntax, it renders the entity in the reduced size inline style: $\binom n k$ which  does not endorse.

To render compound arguments, braces are needed to delimit the parameter when using, but (confusingly) not.

For example, to render $\dbinom {a + b} {c d}$ the following can be used:

or:
 * $\displaystyle {a + b \choose c d}$

Again, for consistency across, the  form is preferred.