Question

Aceste exerciții.Vă mulțumesc anticipat.​

Answer 1

Răspuns:

$\displaystyle\frac{1}{k+1}C_n^k=\frac{1}{k+1}\cdot\frac{n!}{k!(n-k)!}=\frac{n!}{(k+1)!(n-k)!}=\frac{1}{n+1}\cdot\frac{(n+1)!}{(k+1)!(n-k)!}=\frac{1}{n+1}C_{n+1}^{k+1}$

Explicație pas cu pas: