A={1,2,3,4,...,2018}
Cate submultimi de 2 element sun in multimea A?


Răspuns :

A={1,2,3,4,...,2018}

Nr submultimilor cu 2 elemente sunt:

combinari de 2018 luate cate 2=2018!/(2·2016!)=2018·2017/2=2035153