Question

P(n,2) =42 n=? ........................................

Answer 1

P(n,2)=42, find n.
------------
n!/(n-2)! = 42 
n(n-1) = 42
n^2 -n - 42 = 0

(n-7)(n+6) = 0
Positive answer:
n = 7
============
Cheers,