Evaluate n 1Cn-2 If n 15 - JAMB Mathematics 2012 Question

(\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)(n)(n-1)(n-2)!}{3!(n-2)!})

(\frac{(n + 1)(n)(n-1)}{3!})

Since n = 15

(\frac{(15 + 1)(15)(15-1)}{3!})

(\frac{16 \times 15 \times 14}{3 \times 2 \times 1})

= 560