Evaluate n+1Cn-2 If n =15

Evaluate n+1Cn-2 If n =15

Answer Details

$\frac{n+1(n-2)}{(n+1)!}$
$\frac{(n+1)+(n-2)!(n-2)!}{(n+1)!}$
$\frac{(n+1)(n+1-1)(n+1-2)(n+1-3)!}{3!(n-2)!}$
$\frac{(n+1)\left(n\right)(n-1)(n-2)!}{3!(n-2)!}$
$\frac{(n+1)\left(n\right)(n-1)}{3!}$
Since n = 15
$\frac{(15+1)\left(15\right)(15-1)}{3!}$
$\frac{16\times 15\times 14}{3\times 2\times 1}$
= 560