Question

Sa se rezolve ecuatia combinari de n+2 luate cate n+1 = 2 , n aparține numerelor naturale.

Answer 1

Cunoastem formula combinarilor complementare: $C_{n}^{k} = C_{n}^{n-k}$. Deci ecuatia devine: $C_{n+2}^{1}=2$. Adica n+2=2, de unde n=0