Question

Combinare de n elemente luate de cate 1 + 2n =9

Answer 1

$C_n^1+2n=9$
n≥1
n∈N
n∈{1,2..}
$\frac{n!}{(n-1)!*1!} +2n=9\ \textless \ =\ \textgreater \ \frac{(n-1)!*n}{(n-1)!*1!} +2n=9\ \textless \ =\ \textgreater \ n+2n=9\ \textless \ =\ \textgreater \ n=3$