Question

if np4=20×np3 so n =​

Answer 1

NP4 = 12 nP2 Then find n. Ask for details; Follow ... So, _nP_4= 12\times _nP_2. Using formula. \frac{n!}{(n-4)!}= 12.

Answer 2

n(n-1)(n-2)(n-3)=20*(n)(n-1) (n-2)

n-3=20

n=23