Question

 C( n+1 ,2) = C (n-1,2) +15 ise n=?

Answer 1

İpucu:

$$\frac{(n+1)!}{(n+1-2)!\cdot 2!}=\frac{(n-1)!}{(n-1-2)!\cdot 2!}+15\Rightarrow n=?$$