Mathematics · supplementary
Product identity involving permutations for JEE
Meaning of P(n,r) and C(n,r)
Formula
\(\,{}^nP_r\,{}^{n-r}P_s={}^nP_{r+s}\)
Variables: \(n,r,s\) are integers.
Conditions: \(r,s\ge 0\) and \(r+s\le n\).
Sequential ordered selections without repetition.