Aduceti la o forma mai simpla expresia 100 puncte raspuns corect
Apasati pe imagine

[tex]\it=\dfrac{\dfrac{n!}{(n-k)!}\cdot(n-k)!}{(n+1)!}=\dfrac{n!}{(n+1)!}=\dfrac{n!}{n!(n+1)}=\dfrac{1}{n+1}[/tex]