Question

calculez aranjamentele si combinarile si din rezultatul celor doua, il obtin pe n? Help me...

Answer 1

[tex]A_{n}^1+C_{n}^1=10,n\in N,n\geq 1\\ \frac{n!}{(n-1)!}+\frac{n!}{(n-1)!\cdot 1!}=10\\ \frac{(n-1)!\cdot n}{(n-1)!}+\frac{(n-1)!\cdot n}{(n-1)!}=10\\ n+n=10\\ 2n=10\\ \boxed{S: n=5}[/tex]