Question

combinari de 2011 luate cate 2 - combinari de 2011 luate cate 2009

Answer 1

$\binom{2011}{2} = \frac{2011!}{2! - (2011-2)!} = \frac{2011!}{2009! - 2!}$

$\binom{2011}{2009} = \frac{2011!}{2009! - (2011-2009)!} = \frac{2011!}{2009! - 2!}$

\binom{2011}{2} - \binom{2011}{2009} = 0